118 PROCEEDINGS OF THE NATIONAL MUSEUM vol. io4 



be considered cerebral groups extend from brain region anterolaterally 

 to meet the marginal band ; due to a deep fold in the brain region, there 

 may be some micertainty about the cerebral eyes. 



Color: Indeterminable; specimen was dark brown like most pre- 

 served polyclads; this color often bears no relation to the color in life. 



Digestive tract: Pharynx central, elongated, with heavy folds 

 (fig. 81, a); the position of the mouth could not be ascertained due 

 to the opacity of the specimen and was not found on sections. In 

 the other loiown species of this genus, the mouth lies just behind the 

 pharynx, an unusual position in polyclads. 



CoPULATORY apparatus: The male apparatus lies immediately 

 behind the pharynx but could not be seen in the whole specimen; 

 the female gonopore was seen and is indicated in figure 81, a. The 

 copulatory apparatuses are shown in sagittal view in figure 81,6. 

 Due to the condition of the specimen, not all details could be deter- 

 mined. The male apparatus is typical of the genus; the male gono- 

 pore leads into a male antrum, tubular at first, then expanding into 

 a chamber with irregular walls. These waUs contain a number of 

 small prostatic apparatuses, or prostatoids as I have elsewhere called 

 them. There are probably about 25 of these altogether but only a 

 few occur in the median sagittal plane; most of them are in the 

 lateral walls and do not show in figure 81, &, As both Stummer- 

 Traunfels (1933) and Marcus (1950) have figured parasagittal sec- 

 tions of the male apparatus, it appears unnecessary to present such 

 a view here. The prostatoids of A. antillarum differ somewhat from 

 those figured for the two other known species of the genus. In the 

 other species the muscular wall is thin and the glandular interior 

 relatively large. In A. antillarum (fig. 81,c), the prostatoids are of 

 bulbous shape with a thick muscular wall and slender glandular 

 interior. They narrow to a tubular terminal part that appears 

 sclerotized with dense nuclei and that opens on a little projection of 

 the antrum wall. A definite penis papilla is wanting but the dorsal 

 antrum wall presents a rather large eminence. The antrum wall 

 lacks the web of muscle fibers seen in the two other species of the 

 genus; muscle fibers, evidently transverse, were seen only below the 

 main part of the antrimi. Above the antrum lies a prostatic vesicle 

 of angular shape and unusual appearance. It is lined by a tall 

 epithelium but lacks the muscular investment usual to prostatic 

 vesicles. It is accompanied, especially ventrally, by masses of eosin- 

 ophilous granulations, presumably representing prostatic glands. The 

 entrance of the prostatic vesicle into the male antrum could not be 

 found nor was the entrance of the sperm duct into the vesicle trace- 



