194 TONICIA. 



seventh valve is represented in figs. 89, 90 ; and a square millimeter 

 of the girdle is indicated in fig. 95. 



E. HUTTONI Pilsbry, n. sp. PI. 46, figs. 96-100. 



Shell oval, depressed, with convex side-slopes. Color dark brown, 

 the girdle greenish-brown. Valves broadly A-shaped, not beaked, 

 rounded at the ends ; the lateral areas well raised. Entire surface 

 smooth except for a microscopic punctulation and slight growth- 

 lines. Posterior valve (figs. 98, 99) depressed, the mucro plane, 

 central ; posterior margin hardly marginate. 



Interior white, smooth. Sutural plates continuous across the 

 sinus which is indicated by a shallow wave or bay. Insertion- 

 plates blunt, deeply pectinated, the anterior valve having 17, central 

 3, posterior 19 short slits. Eaves very narrow and grooved along 

 the teeth. 



Girdle leathery, bearing numerous short, rigid, dark brown spine- 

 lets. Length 50, breadth 34 mill. ; divergence 135-140. 



New Zealand. 



This species is closely allied to E. nobilis, from which it differs in 

 the proportions of the valves, depressed form, fewer slits, etc. The 

 seventh valve is represented in figs. 96, 100. The specimen 

 illustrated was sent me by Professor Hutton. 



Genus XIV. TONICIA Gray, 1847. 



Tonicia GRAY, P. Z. S. 1847, p. 65, 67 ; Guide Syst. Dist. Moll. 

 B. M., p. 185 (1857), and of authors. Probably Toniehia GRAY, 

 Synops. Contents B. M., 42d edit., p. 153, 1840 (name only.) 



Generic characters. Valves external, all having pectinated inser- 

 tion-teeth ; sinus denticulate ; lateral areas and end valves bearing 

 radiating rows or bands of eye-dots. Girdle leathery, naked or 

 sparsely hairy. Gills extending the whole length of the foot. 

 Type C. elegans Frembly. 



Besides the fundamental characters above recounted, the species 

 of this genus mostly agree in having the valves smooth ish, the 

 second valve notably larger than the following five, and often differ- 

 ently sculptured on the ridge ; the sculpture is generally fine or 

 minute, the colors much variegated or uniform black-brown, and the 

 eaves are hardly spongy. 



From Chcetopleura and Tonicella this genus is very strongly 

 differentiated by the presence of eyes, and also by the more distinctly 



