TETHYS CERVINA BALL AND SIMPSON 39 



Color. The general color is a pale yellowish gray, sprinkled 

 above and on the sides with minute dark brown spots. The 

 dorsal surface of the mantle, covering the shell, is pale grayish, 

 with fine slightly elongate markings of dark brown arranged 

 in inconspicuous radiate lines around the minute opening into 

 the shell cavity. These radiate bands of dark color branch ir- 

 regularly above the periphery of the shell and merge into the 

 general mottling of the body. The sides of the body are marked 

 with a few (eight to ten), irregularly scattered, larger, dark 

 brown flecks, the largest of which is not over i.o mm. in diam- 

 eter. The inner surface of the parapodial lobes is marked with 

 irregular dark brown maculations, alternating with lighter areas. 

 The foot is light brown throughout. These notes were all made 

 from the specimens while in formalin. On being transferred to 

 alcohol, the darker colors gradually became much paler and dis- 

 appeared more or less completely throughout. 



Foot. The foot is very narrow, being strongly contracted, 

 especially midway of its length, there being reduced to 2.0 mm. in 

 width, but broadening in front to 7.0 mm., and behind to 4.0 

 mm., terminating in a short, bluntly pointed tail. The anterior 

 end of the foot is broad and blunt with rounded outer angles. 



Parapodia. The parapodial lobes are 29 mm. in length, 

 occupying nearly three-fourths of the entire length of the animal. 

 They are rather low and not at all prominent, being but 10.0 mm. 

 in extreme height. The lobes are fleshy, their margins thin and 

 slightly undulating, being slightly rugose locally, a condition 

 probably due to contraction. The anterior ends of the lobes are 

 widely separated, the interval being 6.5 mm., which is lessened 

 at the posterior end to 0.5 mm. though the lobes are distinct and 

 not completely joined behind the siphon. 



Mantle. The mantle area is distended and plump, the 

 minute central opening into the shell cavity is borne upon a low 

 papilla, which is rendered more conspicuous by the radiate pig- 

 mentation above described. On the right side the mantle extends 

 in a thin-edged semitranslucent flap over the gill cavity. Poste- 

 riorly its right margin is deeply notched, the edges being elevated 

 and rolled together, forming the prominent excurrent siphon, 

 which extends backward and upward between the edges of the 

 parapodia to a height of 3.0 mm. 



