6 APLYSIIJJ^. 



the European seas, from Upper Norway (Sars) to the 

 Canaries (M' Andrew) , as well as in the Mediterranean 

 and Adriatic. 



Our common Aplysia is gregarious, apparently for the 

 principal reason that keeps herds and flocks together — 

 food, not mutual protection, and still less society. Dr. 

 Johnston fed it on Fucus palmatus and Chrondrus crispus. 

 I observed one individual voiding spines of an Aphrodita. 

 This mollusk is very tenacious of life. I tried to pre- 

 serve one in glycerine ; and for the sake of economy I 

 half filled the vessel with fresh water. It was smothered 

 by the glycerine, and seemed dead ; but on falling into 

 the lower stratum of water, it revived and lived there 

 for several minutes. It swims, in a reversed position, 

 on the under surface of the water. The purple dye is 

 emitted during life only. Spawn-case gelatinous, of a 

 pinkish hue, thread-like, and irregularly convoluted; 

 ova white and very numerous, lying in the middle. The 

 embryonic shell is globular ; it becomes the apex in after- 

 growth, being persistent, as in Teredo. Truncatulina 

 lobatula occurs sometimes on the back of shells taken 

 from living individuals, proving that this part is exposed. 

 Unfortunately there is no typical specimen of A. punctata 

 in the collection of the Jardin des Plantes. Montagu, 

 Fleming, and Alder recognized the name given by 

 Cuvier. That of hybrida, proposed by the late Mr. 

 James Sowerby, is subsequent by three years to punc- 

 tata, and is besides clearly erroneous. Rathke^s species 

 [A. rosea) , described as about an inch long, from deep 

 water off Christiansund, was published before either of 

 the above ; but the peculiar colour, rose-red, has not 

 been noticed in any other European Aplysia, and makes 

 the specific agreement doubtful. At all events the last- 

 mentioned name may be regarded as obsolete. Among 



