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



of the tongue, the presence of a portal heart, and the form of the 

 mucus-gland, in connexion with the genitalia, show its relation- 

 ship to the Dorididse. It seems likewise to have some affinity 

 with the Tritoniadse, as evinced by the great size and character 

 of the jaws, by the imperfect development of the cloak, and by 

 the arrangement of the branchial papillae, which do not extend 

 over the sides of the back as in Eolis, but are confined to the 

 ridges representing the mantle. 



In this animal, then, we see blended the characters of the 

 three great divisions of the order Nudibranchiata. 



EXPLANATION OF PLATES II. AND III. 



Plate II. 



Fig. 1. General view of the viscera of Antiopa Spinolce, the dorsal skin 

 having been removed : a, buccal organ; b, oesophagus; c, stomach; 

 d, intestine ; e, anus ; f,f,f,f, branches from the anterior hepatic 

 canals ; g, g, branches from the posterior hepatic canal ; h, a por- 

 tion of the posterior hepatic canal ; i, internal network of tubes 

 connected with the hepatic apparatus ; j, a gland-like body ap- 

 parently in connexion with the network of tubes ; k, ventricle of 

 the heart ; I, auricle ; the oval boundary represents the extent of 

 the pericardium ; m, portal heart or vesicle opening into the peri- 

 cardium ; n, portions of male organs ; o, portion of mucus-gland 

 attached to the female channel ; p, p', anterior and posterior ova- 

 rian masses ; q, supra-cesophageal ganglions. 



Fig. 2. Side view of buccal organ : a, channel of mouth ; b, oesophagus ; 



c, jaw. 



Fig. 3. Front view of jaws : a, anterior cap or plate ; b t denticulated cutting 

 edge ; c, inner or plain cutting edge. 



Fig. 4. Side view of jaw : a, anterior cap or plate; b, denticulated cutting 

 edge. 



Fig. 5. View of jaw with the cutting edges seen in front : a, anterior plate 

 or cap ; b, denticulated edge ; c, plain edge ; d, point of attach- 

 ment or fulcrum. 



Fig. 6. Tongue removed from the muscular support : a, anterior portion 

 exhibiting rows of spines ; b, posterior tubular portion. 



Fig. 7- Tongue spread out, exhibiting the rows of spines apparently inter- 

 rupted in the centre. 



Fig. 8. Central portion of a single row of spines from the tongue : a, 

 central spine. 



Fig. 9. A single lateral spine more highly magnified. 



Plate III. 



Fig. 1. Digestive apparatus: a, buccal organ; b, oesophagus; c, stomach; 



d, glandular portion of the same ; e, intestine ; /, anus ; g, g, an- 

 terior branches of the anterior hepatic canals; h, h, posterior 

 branches of the same ; i, i, posterior hepatic canal, giving branches 

 to the posterior portion of the body ; j, branch from the posterior 

 hepatic canal crossing the back in front of the anus ; k', ramus- 

 cules leading to glands of papillae ; k, three glands of the papillae 

 in connexion with the ramuscules, the rest of the glands having 

 been removed. 



