46 MacFarland Preliminary Account of Dorididas. 



front of the branchial plumes and sloping rapidly into the broad bluntly 

 rounded tail, in front more gradually ; dorsum everywhere thickly set in 

 irregular rows with short blunt tubercles, cylindrical or with slightly ex 

 panded apices; frontal margin narrow, closely set with tubercles continued 

 behind the rhinophores as a tuberculate ridge diminishing in prominence, 

 the dorso-lateral ridge being posteriorly marked only by an irregular row 

 of tubercles curving upward toward the median line behind the branchiae 

 and meeting the mid-dorsal row of the tail ; foot narrow, linear, the sides 

 nearly parallel, in front truncate, undivided, behind tapering abruptly. 

 Ground-color white or yellowish-white, with irregularly scattered small 

 dark brown spots, or entirely white ; dorsum and sides sprinkled every 

 where between the tubercles with minute dots of pure white. 



Mouth small, inconspicuous, oral tentacles small lobe-like ; rhinophores 

 simple, cylindrical, truncate, completely retractile within prominent tuber 

 cular sheaths, the margin high on the outer side, low on the inner; be 

 tween the rhinophores a median longitudinal row of tubercles ; branchial 

 plumes 3, small, tripinnate, each one protected by a large irregularly tuber 

 culate lobe on its outer side. 



Length of large individual 13 mm. ; width, 3.5 mm. ; height, 4 mm. 



In the roof of the mouth a broad thick quadrangular mandibular plate, 

 the anterior edge thick and straight, the posterior thin and rounded; a 

 narrow girdle of fine rod-like cuticular thickenings guarding the opening; 

 radula broad, deeply grooved; teeth in 16 to 22 rows of 17 teeth each; 

 rhachis narrow, naked, pleural teeth 17, similar in form, strongly hooked, 

 the shaft with the usual thin wing-like process on the inner margin. 

 Glans penis and canal of vas deferens clothed with very minute, densely- 

 set hooks. 



Found under overhanging rocks between tide marks. Very sluggish in 

 movement, avoids the light and soon dies in captivity. 



Laila gen. nov. 



Body depressed; frontal and lateral margins narrow, set with club- 

 shaped papillae ; rhinophores retractile ; clavus perfoliate ; branchial plumes 

 few, tripinnate, non-retractile into sheath, tentacles blunt, canaliculate ; a 

 flattened sub-marginal ridge on each side of anterior end of body just be 

 hind and above the tentacles; no labial armature nor mandibles; radula 

 not narrow, the rhachis with a single series of flattened spurious teeth ; 

 first pleural tooth slender, hook-like, the second large, the remainder 

 smaller, flattened. Glans penis armed. 



This new genus is proposed for the reception of the following described form 

 as its type. It is allied to the genera Triopha Johnston and Jssa Bergh, 

 but differs from the first in the character of the frontal appendages and in 

 the presence of spurious teeth upon the radula. From /ssa it differs in the 

 absence of mandibles, and from both in the presence of the sub-marginal 

 flattened ridge or lobe. 



