POLYCLADS OF THE EAST COAST PEARSE 71 



polyclad and its relations as an oyster pest, it is discussed here but 

 briefly. It is common on oyster beds, especially in summer and dur- 

 ing dry periods when estuarine salinities are high, from Apalachicola 

 Bay along the coast of Florida to Indian River. Palombi (1936) 

 has described JS. tenax from Apalachicola Bay. After examining 

 specimens from the same locality and comparing them with others 

 from the localities from which he describes S. inimicus, I am con- 

 vinced that all belong to one species. The characters that Palombi 

 cites as different are variable. Perhaps this may be explained by 

 the fact that he studied two lots of worms; one was preserved in 

 alcohol, the other in formol. 



STYLOCHUS FLORIDANUS, new species 



Figure 24 



Body of largest specimen observed alive, expanded and actively 

 creeping; length, 53 mm; width, 27 mm. Five preserved specimens 

 measure : 31 by 24.5, 30 by 22, 29 by 21, 23 by 22, 20.5 by 13.5 mm. 

 The margins of the body are always more or less thrown into small 

 folds. The nuchal tentacles are 0.7 mm long when extended. They 

 average about a fifth of the length of the body from the anterior end. 

 They are conical, and each tapers to a rather sharp tip. The enteron 

 has a median stem and branching lateral caeca, which extend to near 

 the margins of the body ; the mouth is on the median line about two- 

 fifths of the length of the body from the anterior end ; the pharynx 

 is thrown into about 10 pairs of lateral folds. There are groups of 

 from 40-odd to more than 100 eyes in and about the base of each 

 nuchal tentacle. A more or less circular group of about 160 eyes 

 surrounds the brain and leaves a clear space in the middle. Periph- 

 eral to this group, eyes are scattered, and these decrease in number 

 centrifugally. Many marginal eyes extend completely around the 

 body. These are more numerous and somewhat larger toward the 

 anterior end and are least numerous at about the junction of the mid- 

 dle and posterior thirds. 



The male genital opening is about 0.5 mm in front of the female 

 opening. Both are on the median line about one-seventh of the length 

 of the body from the posterior end. Anterior to the male opening 

 there is a short conical penis and a pyriform prostate gland. The 

 vasa deferentia coil along the lateral margins of the pharynx, unite 

 posterior to it, and enter the penis through a sinuous tube. The 

 gonads and uteri do not show well in any of the specimens available. 

 Behind the female opening there is a small globular vesicle. 



The color of living specimens is pink. The dorsum is covered 

 with small pink spots, which measure 0.1 by 0.1 mm to 0.1 by 0.6 mm 



