26 Mr. A. Hancock on the Anatomy of Antiopa Spinolse. 



favoured with some from thence through the kindness of M. 

 Verany ; and having made careful dissections of them, and of 

 others from the coast of Cornwall, we have satisfied ourselves 

 that no character exists to distinguish the Italian from the En- 

 glish specimens. The anatomy is the same in both, and all the 

 external parts agree. 



In 1849 M. Emile Blanchard gave a full account of the ana- 

 tomy of Janus Spinola in the ' Annales des Sciences Naturelles/ 

 3 e serie, t. 10. My dissections, however, have brought to light 

 numerous and important details which do not coincide with those 

 given by that anatomist, otherwise I should not have deemed 

 it necessary to draw up the present memoir. These differences 

 will be noticed after the description of each organ ; therefore it 

 is only necessary to state here, that the most important of them 

 relate to the digestive system and to the reproductive organs. 



Antiopa Spinolce* (the name by which our animal must be now 

 designated, the generic appellation of M. Verany having been 

 previously used) belongs undoubtedly to the family Eolididse, as 

 defined in the ' Monograph of the British Nudibranchiate Mol- 

 lusca/ now being published by the Ray Society, though it ex- 

 hibits some characters approximating it to Doris and Tritonia. 

 Antiopa differs in many respects from Eolis, both externally and 

 internally. The body is upwards of an inch long; it is ovate, 

 a little depressed, and tapers to a point behind, with the sides of 

 the back carinated, indicating the presence of a cloak. The 

 branchial papillae are arranged along the carinse and pass round 

 in front of the head ; extending posteriorly a little behind the 

 anus, which is placed in the median line of thel)ack, near to the 

 termination of the body. The generative organs open on the 

 right side. The dorsal tentacles are laminated and united at 

 the base by a fleshy crest. 



Digestive System. — The oral opening is rather large, and is 

 placed on the inferior surface of the head ; it is guarded by a 

 fleshy lip divided behind, and leads by a short canal to the 

 buccal mass (Pis. II. and III. fig. 1 a), which is very large, of a 

 lozenge-form when viewed from above, and somewhat depressed. 

 It is very compact and firm, having the jaws exposed at the sides 

 (PI. II. fig. 2 c), and is provided with numerous powerful mus- 

 cles for their motion, and for advancing and retracting the whole 

 apparatus. The jaws (fig. 3) are of great power, being equal in 

 size to the buccal mass, and give to it its proper form. They are 

 not mere thin plates as in Eolis, but are of considerable thick- 



* As this paper was passing through the press, I have learnt that M. 

 Delle Chiaje was the first to discover this animal, and that he had described 

 it under the name of Eolidia cristata. His specific denomination will 

 therefore have to be adopted. 



