134 BULLKTIN OF THK BUREAU (tK FISHERIES, 



Genus 11. lAILA MacFarland. 



Latta MacFarland, op. cit., p. 40. 



Body depressed; frontal and lateral margins narrow, set witli club-shaped papilla;; rhiiiophoresretrar- 

 tile, clavus perfoliate; brani-hial plumes few, tripinnate, nonretractile into a sheath; tentacles blunt, 

 canaliculate. A flattened submarginal ridge on each side of the anterior end of the body just behind 

 and aVjove the tentacles. 



No labial armature nor mandibles. Radula not narrow, the rhachis with a single series of flattened 

 spurious teeth; first jileural tooth slender, hook-lilve, tlie second large, the remaining lateral teeth 

 (10-13) smaller, flattened. 



Glaus penis armed. 



This genus was proposed for the reception of the following form. It is allied to the gen. ra 

 Triopa Johnston and Issa Benr'i, but differs from the first in the character of the frontal appendau-i- 

 and in the presence of spuriou- teeth on the rhachis of the radula. From Issa it differs in the absence 

 of mandibles, and from l)<)th in tlie jjresence of the submarginal flattened ridge or lol)e. 



12. Liaila cockerelli MacFarland. 



[IM. XXVII, Hks. l.i; I>1. XIX, figs. 4.T-50.] 

 Laila aickerelU MacFarland, op. cit., p. 47. 



Body elongate, depressed, the ends rounded, the back slightly convex, the mantle margin promi- 

 nent, overlapping the foot everywhere except behind. 



Dorsum rounded (pi. .X'.'cvii, fig. 1.5), gently sloping to sides and anterior and i>osterior ends from 

 region of the heart. Pallial margin bearing closely set, stout, club-shaped papilla? arranged in sliort 

 oblique rows of 3-1 papillse in each, increasing progressively in size from the outermost ones toward 

 the median line. Length of papillse 1-6 mm., breadth up to 1 mm. Each papilla is supported by an 

 axial column of strong sjjieules. Median portion of dorsum with numerous scattered low tubercules 

 of varying size, the largest near the median line, between them the surface smooth. 



Head M-ide (pi. xix, fig. 4.5), sloping above, the frontal margin prominent, bearing papilla' similar 

 to those of the sides of the mantle, the mouth opening large with consi>icuous fleshy, plicated lips. 

 Along the side of the head and anterior end of the body on each side a fleshy, flap-like subpallial 

 ridge (pi. xix, fig. 45a), its anterior end just behind and slightly above the base of the oral tentacles, 

 close Ijelow the pallial margin and parallel to it. The anterior and posterior ends of the ridge are 

 rounded, its margin smooth. Length of ridge 2 mm., width 0.5 nmi. Tentacles cylindro-conical, 

 truncate, grooved on upper surface throughout the entire length. Length about 2 mm., diameter at 

 base 0.7 mm., at apex 0.3 mm. 



Foot linear, abruptly pointed behind and extending beyond the mantle, its margins thin and broad, 

 in front squarish, slightly emarginate, the corners rounded, deeply bilabiate, the upper lip projecting 

 beyond the lower and slightly cincave (pi. xix, fig. 45.) 



Ehinophores retractile within smooth margined sheaths. Stalk and clavus of nearly equal length, 

 tapering to a blunted apex, the clavus slightly dilated, perfoliate with about 13 leaves. 



Branchial plumes 5, nonretractile into cavity, tripinnate, in an incomplete circle the center of 

 which is occupied, by the anal papilla. Renal opening at light of anal papilla and near its base. 



General color yellowish white, slightly translucent. Clavus of rhinophores, processes of pallial 

 margin, and tail tipped with deep orange red, the branchial plumes and dorsal tubercules occasionally 

 flecked with the same color. Dorsum marked with irregular network of transparent lines upon the 

 whitish background, the effect of the multitudinous spicules shining through the skin. 



Total length 20 mm., width 7 mm., height 6 mm. in the largest individual taken. 



Pharyngeal bulb small, flattened, oval in shape, the radula sheath projecting slightly behiml. 

 Length 3 mm., width 2 mm., height 1 mm., in an individual of 15 mm. length. Lip disk directed 

 obliquely downward, strongly convex, covered by thin colorless cuticula, the opening vertical, slit-like, 

 with a slight T-shaped widening at dorsal and ventral margins, formed by shallow grooves at either 

 side. .\ slight ring-like thickening of the cuticle marks the opening; behind this the cuticle has a 

 faint tesselated apjiearance. Ko distinct mandibular plate present. 



