544 PROCEEDINGS OF THE NATIONAL MUSEUM vol. los 



systematically collected. Species from this area are widely scattered 

 in the literature. Articles dealing specifically with Micronesian poly- 

 clads are those of Kato (1943) and Hyman (1955b). Kato listed 

 three new and fom* known species from the Palau Islands, of which 

 only one was recovered in the present material, and Hyman 

 two new and two known species from Micronesia, of which one has 

 been recovered here. The prevalence of known species in even such 

 small collections indicates a wide distribution of polyclad species 

 in the Indo-West Pacific area. 



Taxonomic categories have been defined in previous publications, 

 especially Hyman (1953a), and definitions will not be repeated here. 

 Only categories not found in previous articles will be explained. 



Order PoLYCLADiDA 



Suborder Acotylea 



Section Craspedommata 



Family Latocestidae Laidlaw, 1903 



Latocestus pacificus Laidlaw, 1903 



FiGUEE la-e 



Material: One specimen collected by the Stanford team at the 

 Palau Islands, Sta. 64, from a small bay at the south end of the la- 

 goon of Eil Malk, Aug. 7, 1955. 



General characters: The worm, 11 mm. long and about 1 mm. 

 wide, has the strap shape typical of the genus (fig. la). It is brown, 

 of thick, opaque consistency. The numerous small eyes begin well 

 posterior to the anterior margin as a median band, irregular at first 

 but becoming bilateral in arrangement before reaching the brain; 

 anterior to the brain the eyes spray out over the anterior end as usual 

 in the genus (fig. 16). The marginal eyes are not well delimited 

 from the frontal eyes but continue for a short distance posterior to 

 the level of the brain. The position of the brain is shown in figure 

 16. Because of the dark, opaque consistency of the worm the exact 

 arrangement of the eyes was difficult to ascertain and, further, little 

 could be seen of the internal anatomy. The short ruffled pharynx 

 with the mouth at its posterior end occurs near the posterior end of 

 the worm as typical of the genus, and between the mouth and the pos- 

 terior margin are seen the male and female gonopores (fig. la). 



CopuLATORY apparatus: The posterior end of the worm was re- 

 moved and sectioned sagittally. The contained copulatory apparatuses 

 are shown in sagittal view in figure Ic and are characteristic of the 

 genus. The free prostatic vesicle with thick musculai* wall and 



