29 December 2011

When barnacles were mollusks

This brightly colored picture of the gooseneck barnacle (Lepas anatifera) is from Edward Donovan's The Natural History of British Shells published in 1799.

Back then, and until the 1830s, barnacles were grouped together with mollusks, simply because they had shells as do most frequently encountered mollusks. Barnacles are actually arthropods, because they have jointed appendages like insects and their relatives. This post was about a barnacle on a snail shell.

Here is the title page of Donovan's book. It is available on Google Books.

19 December 2011

Old Discus ruderatus

As part of an ongoing study, which is almost finished, I've been measuring shells of several species of Discus. Among the species included in the study is the European Discus ruderatus. Here are the labels of 2 old lots from the Carnegie Museum of Natural History in Pittsburgh.

The oldest date I can make out on the labels is 7/30/01; undoubtedly, that was 1901. And the stated location "Klausenberg, Transylvania, Hungary" was presumably the city of Cluj in Romania.

The 2nd lot was collected in Grisons, a canton in Switzerland, in August 1852.

The previous post in this series was about Discus rotundatus.

14 December 2011

When taxonomy was much simpler

An excerpt from the entry for "Limax" in the 3rd edition of the Encyclopaedia Britannica published in 1797:

LIMAX, the Slug, or Naked Snail; a genus of insects belonging to the order of vermes mollusca...There are eight species, distinguished entirely by their colour; as the black slug, the white slug, the reddish slug, the ash-coloured slug, &c.

07 December 2011

Observations of Deroceras laeve

One highlight of tonight's malacology-related activities at home was the filming of 3 individuals of the slug Deroceras laeve while they were having their meals.

The slugs, who had been starving for several days, were on a glass plate that I had coated with corn starch. They seemed to really enjoy the starchy meal. Here is a frame from a film footage of one of the slugs taken thru the glass and the starch layer.

The arrow #1 is pointing to the jaw, while the arrow #2 is, I believe, to the tip of the radula that the slug was using to scrape the starch off the glass.