120 PROCEEDINGS OF THE NATIONAL MUSEUM vol. i04 



Family Stylochidae Stimpson, 1856 



Genus Stylochus Ehrenberg, 1831 



Stylochus megalops (Schmarda), 1859 



Figure S2,a,b 



Dicelis megalops Schmarda, 1859, p. 15, pi. 2, fig. 30. 

 Stylochus heteroglenus, Schmarda, 1859, p. 34, pi. 7, fig. 77. 



Stylochus megalops, Stummer-Traunfels, 1933, p. 3488, figs. 1-4; p, 3556, figs, 

 126-128. 



Material: One specimen from the Fish Hawk Puerto Rico Ex- 

 pedition. 



Form: Almost circular, 20 mm. long by 17 mm., wide but evidently 

 much contracted; the Schmarda specimens were broadly oval, measur- 

 ing 14 by 9 and 12 by 9 mm.; margins much ruffled and folded, 

 probably the result of contraction; with a pair of nuchal tentacles, 

 contracted as usual to a bulbous shape (fig. 82,a). 



Eyes: There are numerous eyes in each tentacle, also some around 

 their bases; the cerebral eyes are rather scanty, consisting of loose 

 groups between the tentacles; frontal eyes are lacking; the marginal 

 band is fairly wide and extends back less than half the body length 

 (fig. 82, a). On account of the many folds and general opacitj^ of the 

 specimen, the eyes were not distinguished with entire satisfaction. 



Color: The specimen shoAvs the usual dark brown color common 

 to preserved polyclads. According to the original colored figures of 

 Schmarda, the species is light brown with dots and reticulations. 

 However, these figures appear to have been made from preserved 

 material, not from life. 



Digestive tract: The pharynx is central with a few broad, much 

 ruffled lateral folds. On account of the darkened condition of the 

 specimen no other details of the digestive tract could be ascertained. 

 The mouth is beneath the posterior part of the pharynx (fig. 82,a). 



CopuLATORY apparatus: Lics close behind the pharynx, therefore 

 far from the posterior margin (fig. 82,a). In the whole specimen the 

 outUne of the prostatic vesicle could be seen in this position; farther 

 on, the uteri extended anteriorly to either side of the pharynx (fig. 

 82,a). Sagittal sections were made of the postpharyngeal region. 

 They revealed an unfortunate fold between the male and female ap- 

 paratuses that somewhat distorted the relations of these parts, but 

 the specimen proved in fair histological condition. The male appa- 

 ratus was found to have been cut nearly sagittally but, owing to the 

 fold just mentioned, the female apparatus was cut crosswise. The 

 details of both structures agree well enough with the two figures fur- 

 nished by Stummer-Traunfels (1933), but they diflFer in small details. 



