1912.1 



NATURAL SCIENCES OF PHILADELPHIA. 



459 



Family PLANOCERID^E Lang, 1884. 



With nuchal tentacles. Mouth about the middle of the body. 

 Penis directed backward. 



Genus PLANOCERA. de Blainville, 1828. 



With slender, pointed nuchal tentacles well removed from the 

 anterior end of the body. Separated sex openings a considerable 

 distance from the posterior end. Eyes on bases of tentacles and 

 in the brain area. 

 Planocera californica sp. nov. 



This species is fairly abundant along the southern coast of Mon- 

 terey Bay, and to the south for at least thirty-four miles. It usually 

 occurs above mean tide in crevices of the rocks and beneath boulders 

 on the beach. The ground color is light transparent olive, upon 

 which a system of chocolate-colored markings occur, corresponding 

 closely to the position of the digestive tract. A long bar of this 

 color extends along the mid-dorsal line from the front of the brain 

 to the reproductive openings, sending off lateral branches along its 

 course which ramify to the body margin. On the ventral surface 

 of the animal the tissues are unpigmented and the somatic muscles 

 are of whitish cast and so opaque that the internal organs are 

 invisible. 



The largest specimen (PI. XVIII, fig. 39) measured 24 mm. in 



length by 14 mm. in width, and the oval or broadly elliptical body 



is of very firm consistency. Nipple-like retractile tentacles occur 



immediately before the 



end of the first fifth of . . 



• • •• 



the body. The eyes 

 (text fig. 1) occur in the 

 two usual groups — one, 

 consisting of about 

 ninety large ocelli in 

 each of the tentacle clus- 

 ters distributed in and 

 about the tentacles in 

 somewhat spindle- 

 shaped areas diverging 

 anteriorly, while the 

 other, the cerebral set, 

 comprises about sixty- 

 five smaller eyes, commencing at the level of the posterior border of 



4 



• • ».. . 



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.**-.. 





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Fig. 1. — Eyes of Planocera californica. 



