Helminth Fauna of the Dry Tortugas. 75 



specimens they are distributed generally in the posterior part of the body 

 behind the genital sucker. They are dendritic, or, in the older specimens, 

 represented by small, compact masses. The excretory vessels begin 

 anteriorly in 2 lateral vessels beside the oral sucker. These branches 

 unite dorsal to the ovary a little in front of the middle. Thence a single 

 median vessel extends to the posterior end, near which it enlarges into a 

 muscular excretory vessel. The living worm is characterized by having 

 numerous, conspicuous, small, tube-like structures in the neck. These 

 were wrongly called excretory vessels in the original description of the 

 species. I am not altogether sure of their real nature, but have reason 

 to think them to be similar to the cells which elsewhere in this paper are 

 called yolk-forming cells. In sections they are seen to be slender, long- 

 pyriform, and pyriform bodies, not staining in hsematein but staining 

 strongly in orange G, with a fine granular structure. In transverse 

 sections these pyriform bodies are peripherally placed with their small 

 ends inserted in the body-wall. Nuclei were indistinctly seen in some of 

 them. In the central portion of the sections of the neck were somewhat 

 similar bodies but more coarsely grained and less elongated. In some 

 of the sections the more coarseh* granular bodies strongly suggest an 

 intermediate stage between the fine granules of the peripherally placed 

 bodies and the vitelline glands, as in the case of Deradena ovalis (fig. 169). 

 If this is a correct interpretation we have here an example of yolk- 

 formirg cells in the neck. In that case the tube-like structures which 

 appear to be penetrating the body-wall would turn out to be slender 

 cells with the small ends peripheral and the large ends central, the re- 

 semblance to tubes penetrating the body-wall being deceptive. The 

 folds of the uterus are very voluminous and fill up all the postero-median 

 part of the body. In life the beginning folds on the left side are opaque- 

 white, the next towards the posterior end on the right side are light 

 yellow, shading into amber and smoky brown, becoming much darker 

 toward the anterior. The metraterm was traced to the prostatic portion 

 of the cirrus-pouch, but it was not seen to enter it. It appears to enter 

 the genital pit in front of the genital sucker. 



Dimensions of Tortugas specimen, life: Length 1.75; breadth 0.70; 

 oral sucker 0.14; genital sucker o.io; ova 0.017 by 0.007. 



Host, Ocyurus chrysurus: July 10, 1907, 3 fish, 2 trematodes, one 

 with ova and one without. 



Stegopa globosa gen. et sp. nov. (Figs. 205-207.) 



Etymology: Tr/;'w, to protect; "'->/', an opening. 



The anatomy of these trematodes has been but imperfectly made 

 out, mainly on account of the immense number of ova which obscure 

 the various organs. The following incomplete description, it is to be 

 hoped, will make future recognition of these minute forms possible. 



Body nearly spherical ; oral sucker three or more times the diameter 

 of the genital sucker; pharynx adjacent to oral sucker about equal to 

 genital sucker; intestine not seen; genital sucker median; cirrus, cirrus- 

 pouch, and seminal vesicle not made out; testes 2, transverse or nearly 



