MacFarland Preliminary Account of Dorididx. 47 



12. Laila cockerelli sp. nov. 



Type from Monterey Bay, Calif. No. 181,290, U. S. National Museum. 



Body elongate, depressed, the ends rounded, back slightly convex, man 

 tle margin prominent, overlapping the foot everywhere except behind; 

 mantle margin bearing closely set, stout club-shaped papillae, 1 to 6 mm. in 

 length, arranged in short oblique rows of 3 or 4 in each, increasing progres 

 sively in size from the outermost inward ; each papilla supported by an 

 axial column of stout spicules; median portion of dorsum with numerous 

 low scattered tubercles of varying size. 



Head wide, sloping above, the frontal margin prominent, bearing papillae 

 similar to those of the mantle sides, the mouth opening large with con 

 spicuous fleshy plicated lips ; beneath the mantle margin on each side of 

 the head a fleshy, flap-like sub-pallial ridge its anterior end just behind 

 and slightly above the base of the oral tentacles; length of ridge, 2 mm., 

 width, 5 mm., its edge smooth, the ends rounded ; oral tentacles cylindrical- 

 conical, truncate, the upper surface grooved. 



Anterior margin of foot deeply bilabiate ; rhinophores perfoliate with 

 about 13 leaves, retractile within smooth margined sheaths; branchial 

 plumes 5, non-retractile into cavity, tripinnate. 



General body-color yellowish white, slightly translucent; clavus of 

 rhinophores, processes of mantle margin and tail tipped with deep orange- 

 red, the branchial plumes and median dorsal region occasionally flecked 

 with the same; dorsum marked with an irregular network of transparent 

 lines, the effect of the multitudinous spicules shining through the skin. 



Total length of largest specimen, 20 mm. ; width, 7 mm. ; height, 6 mm. 



Radula nearly colorless, broad with wide median groove. Teeth in 76 

 to 82 rows ; rhachis narrow, with a single series of colorless flattened 

 plates ; pleural teeth 2, the first one a single slender strongly curved vertical 

 hook fitting closely to the second pleural tooth which is strong and heavy, 

 the shaft irregular in form bearing at the anterior end 2 strongly hooked 

 cusps, the inner one smaller, the 2 together forming a crescentic figure ; 

 the lower (posterior) end of the shaft with a slight wing-like elevation on 

 its outer face; uncinal teeth 10 to 13 in number, closely set, pavement- 

 like, presenting from above an arched quadrangular outline, the first 4 with 

 2 pointed cusps at the posterior angles, much reduced and finally disap 

 pearing in the outer ones which become transformed into flattened plates. 

 Glans penis long, cylindrical, armed with 10 to 12 irregular rows of 

 minute thorn-like hooks. 



Occurring under shelving rocks between tide marks along the coast. 

 Not rare. Much smaller individuals of the same species have been col 

 lected at San Pedro, Calif, by Prof. T. D. A. Cockerell for whom the species 

 is named. 



