POLYCLADS OF W. INDIES AND FLORIDA — HYMAN 139 



Genus Acerotisa Strand, 1928 

 Acerotisa multiceliSf new species 



Figures 87,6,c; 88,a 

 Acerotisa sp. Hyman, 1952, p. 199. 



Material: Six specimens from the Smithsonian-Hartford Expedi- 

 tion (No. 21). 



Form: Broadly oval, with rounded ends (fig. 87,6); the largest 

 specimen is 8 mm. long by 6 mm. wide, the smallest, which is never- 

 theless fully mature, is about 3.5 mm. long by 2.5 mm. wide. The 

 middle of the anterior margin shows two slight protrusions bearing 

 the tentacular eyes. 



Eyes: More numerous than in any other species of the genus; as 

 usual they vary in number with the size of the animal. The cerebral 

 clusters form two elongated, somewhat wedge-shaped groups that 

 range from 32 to 35 in the smallest of the available specimens to 45 

 in the largest. The tentacular groups, found on the slight anterior 

 protrusions, range from 42 to 45 in the smaller, up to 50 to 55 in the 

 larger specimens. 



Color: White covered with minute black dots. The dotting is 

 evident in the preserved specimens and is shown in part of figure 87,6. 

 These dots are probably groups of rhabdites. 



Digestive tract: Typical of the genus. The short tubular 

 pharynx occurs in the anterior body third, directly behind the brain 

 and cerebral eye clusters. It leads into the main intestine, a broad 

 tube extending posteriorly in the midline and terminating blindly 

 some distance anterior to the posterior margin. The intestine gives 

 off a limited number of lateral branches (the number could not be 

 exactly determined) that anastomose into an extensive network. 

 This network was evident in some of the specimens and is indicated 

 in part of figure 87,6. An intestinal network occurs in some other 

 species of Acerotisa, namely, A. meridianus Ritter-Zahony, 1907; 

 A. typhlus Bock, 1913; and A. arctica Hyman, 1953. 



Marginal glands: A distinctive feature of this species is the pres- 

 ence of a row of flask-shaped glands along the entire margin except 

 for the tentacular protrusions, as shown in figure 87,6. In sections 

 these glands appear as empty flasks opening through the epidermis. 

 They are located in the mesenchyme internal to the epidermis (fig. 87,c) . 



Copulatory apparatus: A set of sagittal sections was prepared 

 and also a set of transverse sections, but neither was entirely satis- 



