Trona stercoraria (Linnaeus, 1758) by diver at night, low tide in seaweed at 3 meters, M’bour, Senegal
Trona stercoraria (Linnaeus, 1758) dwarf. by diver on rocks at 10 meters, Gulf of Guinae, Limbe, Cameroon

Trona stercoraria (Linnaeus, 1758) is a popular cowrie among collectors due to its extreme variability in size, shape, color and even pattern. Its common name the Rat Cowry or Droppings Cowry. Certain populations have overcastings that make for bizarre specimens which may look as if they were infected by disease (and possibly they are). These are common in some locations.
Even with all the variation stercoraria is easily recognized and can’t be confused with any other cypraea. Its coloration could be considered drab (mousy, hence the name Rat). It is certainly not flashy. Typical specimens have a mocha colored base with dark brown chiseled teeth. The dorsum is similar in color and covered with blurred brown blotches. Some specimens are light, others dark in color. Scarce specimens have a largely clear dorsum, others with an irregular pattern while the occasional one has the blotches fused to almost sold and even scarcer almost black. The margins are calloused and both extremities are rostrate. Sizes run from extreme dwarfs of 1″ to giants of about 3.75”. The majority fall between 2 and 2.5″. While typically rhomboid, sone specimens are oval.
There are populations with an extreme hump that were named Trona stercoraria rattus (Lamarck, 1810). Linnaeus call the dwarfs “minima”. Even with all the variation the vast majority have the patterns and shape of the two offered here.
Trona stercoraria is a West African cowry with a restricted range below the Bulge of Africa. Most specimens come from the Gulf of Guinea. It is fairly common in this area and lives in a variety of shallow water habitats.
The two shells were donated by Richard Kent and were obtained from European dealers. Average sized specimens retail for $20-25, dwarfs though much scarcer somewhat less. Large ones go for over $30. Giants and unusual specimens can be found on eBay from $60 to over $300. In fact there is one very dark 95mm specimen with blueish borders listed for sale at $520!

BOOK REVIEW – Cowries by Felix Lorenz

Cowries, A Guide to the Gastropod Family Cypraeidae” by Felix Lorenz

Book Reviewed by Richard Kent

Finally the highly anticipated sequel to “The Guide to Worldwide Cowries” by Lorenz and Hubert has been published. There is both good and bad news about the new book. We need to point out that “Cowries, A Guide to the Gastropod Family Cypraeidae” by Felix Lorenz and published by Conch Books is split into two volumes. At this time only Volume 1 is available.

First the good news. Everything one could possibly want to know about Cowries, live and extinct, is thoroughly discussed. This is the de nitive book on the subject.

The bad news. It’s 644 pages of exhaustive text is intended for the advanced collector. Photographs are minimal; Volume 2 will be the photo book. The price is a whopping $199 retail. The way the volumes are split up, readers will need to purchase both.

The rst 181 pages cover in seven chapters: Cowries and Man, Animal Morphology, Reproduction and Development, The Adult Shell, Habitat and Distribution, DNA, and Cowrie Evolution. It’s fascinating and essential reading that one needs to make the most out the second half of the book.

The balance of the book is a systematic Cowrie
Identification Guide, updating the original “Guide” to the present with numerous new subspecies and species. Collectors will especially get new insight on South African and Australian Cowries. Every species is given scientic name, synonyms, cited references, size range, habitat, distribution and a discussion. The descriptions are concise, cut and dry. One misses the air that Wells had in his book on Cones. There are also comparison charts and maps. Lorenz illustrates each species and subspecies with a photo of the dorsum and base of a typical specimen. All are shown the same size so the minute Cypraea microdon is illustrated at an identical size as Cypraea tigris. Even though all are shown the same size, the length of the discussion for each species varies greatly. It is obvious Lorenz has his favorites! He chooses to devote much space to discussions on nomenclature and DNA. Lorenz is what is known as a “splitter” (as opposed to “lumper”) and has introduced dozens of new names himself. At times the detail in these discussions can be overwhelming, even to an advanced collector.

Collectors could nd much that is controversial and open to debate. One of several instances that stood out to me is that according to Lorenz, Cypraea tigris tigris is an Indian Ocean cowrie whereas Cypraea tigris pardalis is the Philippine variety, but he fails to cite the original descriptions and type specimens to back this up. Having dealt with shell dealers for years, pardalis is an all white tiger with minimal black spotting and no dorsal line, just like the one illustrated in the groundbreaking Burgess book. It would be interesting to see that if one dozen tigers from various populations in the Indian Ocean were mixed with one dozen from the Paci c if any expert could correctly separate them. Lorenz says they have different DNA.

I read the book cover to cover taking a full week. Because I am an advanced collector I nd the book essential. It greatly added to my understanding and enjoyment of the hobby. I can’t wait for volume 2 with all the photos to be published.

A word to Mr. Lorenz – take only the information that is essential to the beginning and casual collectors and publish a condensed, concise photo guide. The hobby needs such a book. It will be a best seller!