SOME POLYCLAD FLATWORMS 



FROM THE 



GALAPAGOS ISLANDS 



By Libbie H. Hyman 1 



MARINE 



BIOLOGICAL 



LABORATORY 



LIBRARY 



30KH0LE MACS. 



I W. K I. 



A small collection of polyclads taken by the Allan Hancock Pacific 

 Expeditions on three visits of the Velero III to the Galapagos Islands 

 furnishes the basis for the present article. The collection consists of seven 

 vials, found to contain five species, one known and four unknown. The 

 known species, here recovered, is Prosthiostomum parvicelis Hyman, 

 1939, and two additional species, not represented in the present material, 

 have been recorded from the Galapagos Islands in the literature: Em- 

 prosthopharynx opisthoporus Bock, 1913, and Pseudoceros splendidus 

 Stummer-Traunfels, 1933, reported by Plehn (1896). All types from 

 the present study have been returned to the Allan Hancock Foundation 

 for permanent deposit. 



As the terminology herein employed, and familial and generic de- 

 finitions, are given in my article "The Polyclad Flatworms of the Pacific 

 Coast of North America" (Hyman, 1953), it seems unnecessary to re- 

 peat them here. Definitions will be given only for genera not treated in 

 that article. 



Family Latocestidae 



Genus LATOGESTUS Plehn, 1896 



Definition. — Latocestidae of long slender shape; pharynx near the 

 posterior end, hence with long main intestine extending forward from the 

 pharynx to the brain region; copulatory complex behind the pharynx, 

 hence very close to the posterior end ; with or without spermiducal bulbs ; 

 prostatic vesicle extending anteriorly from the penis papilla; Lang's 

 vesicle present. 



Type species. — Latocestus atlanticus Plehn, 1896. 



Latocestus galapagensis, new species 

 Figs. 1 and 2 



Material. — There were three vials of this species, one containing six 

 specimens, collected at station 166-34, Black Beach, Charles Island, 

 January 19, 1934; one with one specimen taken at station 71-33, James 



1 American Museum of Natural History, New York. 



[183] 



