1912.] NATURAL SCIENCES OF PHILADELPHIA. 463 



Genus STYLOCHOPLANA Stimpson, 1857. 



Stubby tentacles about one-fifth the body length from the anterior 



end. Male and female genital pore united and well removed from 



v posterior end of body. Eyes on basis of tentacles and in brain area. 



Stylochoplana gracilis sp. nov. 



This very small species is represented by eight individuals, all of 

 which were taken on the broad thalli of Macrocystis pyrifera, growing 

 in the vicinity of the wharf of the Del Monte Hotel, near Monterey. 

 It was most often found on surfaces encrusted with colonies of bryozoa. 

 The color of the dorsal surface is pale brownish-yellow or buff, 

 fading gradually as the margins of the body are approached. The 

 ventral surface is unpigmented, yet the tissues are so opaque that 

 little more than the digestive tract is visible in living material. 



The largest specimen measured 7.5 mm. in length by 3 mm. in 

 width. In every case the outline of the body is cuneate-oval (PI. XII, 

 fig. 2) with a broad semi-truncate anterior margin, while the posterior 

 end is usually pointed. The mouth is located slightly in front of 

 the middle of the body. The penis is directed backward. Finger- 

 like nuchal tentacles are placed at the end of the first body fifth. 

 The eyes (PL XIV, fig. 20) are arranged in two groups. The ten- 

 tacle pair, each consisting of about four medium-sized eyes, is confined 

 to the basal portion of the tentacles, while the cerebral clusters, 

 fairly well differentiated, comprise approximately fourteen eyes each. 



The mouth (PI. XII, fig. 2) opens into the pharynx, which is 

 considerably nearer the anterior than the posterior end, and covers 

 an extent equal to one-fourth the length of the animal. The pharynx 

 is slightly folded only, though the resulting inconspicuous lobes are 

 relatively numerous. The main gut is narrow, of moderate length, 

 and possesses usually seven pairs of intestinal branches with alter- 

 nating diverticula. The posterior pair terminate the gut immediately 

 behind the pharyngeal pocket, but anteriorly a median branch 

 continues forward across the brain. All of the branches immediately 

 anastomose and continue to do so until close to the margin of the 

 body. 



The brain holds a position at the commencement of the second 

 body sixth, but as the main nerve trunks to which it gives rise are 

 typical and their ramifications are very difficult to follow, no serious 

 attempt has been made to examine critically this particular system. 



The testes, for the most part ventrally placed, have not been seen 

 to connect with sperm capillaries, but the vasa deferentia, on the 



