EI.IOT : NUniBRANCHS AND TECTIBRANCHS FROM INDO-PACIFIC. 30I 



and the absence of swimming lobes. It swims by strokes of its 

 powerful tail, and the comparatively small wings seem not to be used 

 for purposes of locomotion, but form a chamber which protects the 

 fragile shell and the viscera below it. In internal anatomy the two 

 genera are similar, but Lophoceniis has a large buccal mass and a 

 moderately large circular crop, whereas in Lobiger the buccal mass is 

 small and the elongate coiled crop enormous. Much the same differ- 

 ence is exhibited in the digestive organs of Cyerce and Fhyllobranchus, 

 which are otherwise closely related. Lobiger and Lophocercus have 

 also each a characteristic form of salivary gland. 



Lophocercus is recorded from several parts of the Mediterranean, 

 including the Aegean, the West Indies, Cape Verde Islands, Zanzibar, 

 Ceylon and Southern India, the Sandwich Islands, Tahiti, and the 

 New Hebrides. Six species have been described : Z. sieboldi (or 

 olivacea), antillanim, viridis, krohni, delicatulus, and hargravesi. Of 

 these, L. krohni and L. hargravesi are founded on shell characters of 

 doubtful validity; and Z. delicatulus (G. & H. Nevill, 1869) seems 

 the same as Z. viridis (Pease, 1861). The remaining species are 

 closely allied to one another, but Bergh [I.e.) somewhat doubtfully 

 recognizes Z. sieboldi and L. antillarum as separate, the difference 

 being chiefly in the colour. The Indo-Pacific form seems entitled to 

 specific rank, though by no means sharply distinguished. The most 

 decided difference is in colour, as the body bears blue spots and 

 ocelli, which are absent in the Atlantic and Mediterranean forms. 

 Other points of difference in the shell, genitalia, and other organs 

 are noted below, but in most cases it is hard to be sure that they are 

 really permanent and characteristic of the species, not merely varia- 

 tions depending on age or accident. Perhaps in the Pacific specimens 

 the shell is narrower, the body more plentifully covered with papillae, 

 and the wings more distinctly raised and united into a chamber 

 enclosing the shell. 



Lophocercus viridis Pease. (Plate V., fig. 5). 



Pease, Proc. Zool. Soc, 1861, p. 246 ; Amer. Journ. Conch., vol. 4, 

 p. 74> pi- 8. fig- i> 2, pi. 12, fig. 25. 



Six specimens from Zanzibar, dredged in one to two fathoms at low 

 water. The notes on the living animals are as follows : — " Colour 

 bright yellowish green, covered with rings of dull yellow. The inside 

 of each ring is bright blue, and each blue area has a clear black spot 

 in the centre. There is a line of pinkish white projecting points 

 down each side, above which, on the edges of the wings, is a similar 

 line of pinkish zigzag points. These two lines meet behind and are 

 continued as a median dorsal line down the tail. The rhinophores 

 are the same colour as the body on their outer sides, the blue spots 



