POLYCLAD FLATWORMS — ^HYMAN 77 



the best figure of the copiilatory apparatus is that of Kato which, 

 however, also seems a little schematized. Therefore, I present 

 figures of the copulatory apparatus of one of my series of sections. 

 As the male and female systems are very far apart in this species, 

 as shown in Kato's figure, one cannot represent them on one drawing 

 except on a reduced scale. Consequently the male apparatus is 

 shown in figure 4,a and the female apparatus in figure 4,6. These 

 may be compared with figures in the literature. It appears super- 

 fluous to describe them in detail, but the following points shall be 

 noted. The penis papilla is smaller in my specimens than in the ones 

 represented by MeLxner; I do not find the wide muscular provision 

 around the distal part of the seminal vesicle that is depicted by 

 MeLxner and Stumraer-Traunfels; I do not find the prostatic glands 

 depicted by these two authors as occurring in the wall of the male 

 antrum, further not recorded by Kato; and in my smallest specimen 

 (length, 16 mm.) the anterior horns of Lang's vesicle are definitely 

 wantmg, so apparently they are present only in the more mature 

 worms. The terminal parts of the spermiducal vesicles acquire 

 muscular walls and hence are to be regarded as spermiducal bulbs. 

 These pursue a tortuous course in the larger specimens. They unite 

 to a common sperm duct that descends and then enters the fusiform 

 seminal vesicle, which ascends diagonally and narrows to an ejacula- 

 tory duct that after a forward bend enters the conical penis papilla. 

 The anterior horns of Lang's vesicle could not be successfully traced 

 in the larger specimen; they are shown in figures in the literature. 



Specimens: Most of the specimens have been returned to the 

 U. S. National Museum. One specimen with typical color pattern 

 has been deposited in the American Museum of Natural History. 



Remarks: Euplana gigas is evidently spread throughout the whole 

 of the vast Indo-West Pacific area and is one of the most common 

 polyclads of that region. It has been recorded from SomalUand on 

 the eastern coast of Africa, Ceylon, the Maldive Islands, Timor, 

 Funafuti, the Moluccas, and Japan, to which list may be added the 

 present record of the Gilbert Islands. The species is apparently 

 absent from the Hawaiian Islands, where its place is taken by an- 

 other large species of Euplana Girard (Hyman, 1954). 



Family Planoceridae Lang, 1884 



Genus Paraplanocera Laidlaw, 1903 



Paraplanocera oligoglena (Schinarda), 1859 



Figure 4,c 



Stylochus oligoglenus Schmarda, 1859, p. 34. 

 Stylochus amphibolus Schmarda, 1859, p. 34, 



