70 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loe 



Differential diagnosis: Of the six described species of Discocelis, 

 the gonopores are separate in only one, namely D. herdmani (Laidlaw) , 

 1940. The present species diflPers from herdmani in the eye pattern, 

 the very long female canal, and the irregular Lang's vesicle. 



Holotype: One whole mount, minus the copulatory apparatus 

 and sections of the copulatory apparatus (sl\ slides), has been de- 

 posited in the U. S. National Museum (No. 25939). 



Remarks: The type species, D. lichenoides, is ver}^ poorly known 

 and the genus is, in fact, based on Lang's (1884) description of 

 D. tigrina (Blanchard). This situation could easily give rise to 

 nomenclatorial difficulties. The family definition here given excludes 

 Semonia, for it appears to me undesirable to include in the family 

 genera that lack tlie characteristic provision of the male apparatus 

 Avith numerous small prostatic structures. The family is then limited 

 to the genera Discocelis, Adenoplana Stummer-Traunfels, 1933, and 

 Coronadena Hyman, 1940. 



Family Latocestidae Laidlaw, 1903 



Juvenile latocestid 



Figures 2,6; 3,o 



Material: One small, juvenile specimen collected at Saipan in the 

 Marianas by P. E. Cloud on May 6, 1949. 



Whole mount features: The worm has the typical appearance of a 

 latocestid, long and slender with rounded ends; it is 11 mm. long by 

 2.5 mm. wide (fig. 3, a). The color appears a dirty white. The mar- 

 ginal band of eyes could not be traced with certainty around the 

 posterior end, but it appeared to stop at about the level of the mouth. 

 As usual in the family, the anterior end is strewn with small eyes to 

 the level of the brain (fig. 2,6). Directly in front of the brain the}^ are 

 aggregated into two linear cerebral clusters. The pharynx is in the 

 posterior body half and broadens posteriorly where it terminates in a 

 rounded part bearing the mouth. 



Copulatory apparatus: As usual in the family, the copidatorj^ 

 apparatus is located in the short posterior region between the posterior 

 end of the phaiyngeal cavit}- and the posterior body margin. The 

 female pore was detectable here in the whole mount, but sections of 

 this postpharyngeal region revealed only traces of the copulatory 

 apparatus. The specimen is thus immature and cannot be placed 

 generically, although it is highly probable that it belongs to Latocestus. 

 The eye pattern appears different from that of described species of 

 Latocestus. 



The specimen mounted whole plus the sections of the postpharyngeal 

 region has been returned to the L^. S. National Museum (No. 25940). 



