20 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. G4. 



MONORYGMA, gpecies. 



Plate 1, fig. 6. 



1900, p. 271. 



1901, pp. 426, 429. 

 1911, p. 586. 



Small cestodes of this genus are recorded in my notes on a few 

 occasions, but the preserved material does not admit of satisfactory 

 specific determination. FolloAving are records not before published. 



Squalus acanthias. 



1910, July 29 : 1. Length of specimen in balsam 3 mm. ; length 

 of bothrium 0.28, breadth of anterior loculus 0.14, posterior loculus 

 0.28 ; bothria with thick, muscular walls. 



Ra^a stabuliforis. 



1904, October 10: 1. Dimensions of alcoholic specimen: Length 

 7.7; bothrium, length 0.42, breadth 0.21; breadth of neck 0.14; dis- 

 tance to firet segment 0.42 : length of first segment 0.04, breadth 0.14 ; 

 last segment, length 0.45, breadth 0.30; last segment fusiform, 

 tapering at each end. 



(U.S.N.M., Helm. Coll. 7670.) 



ORYGMATOBOTHRIUM FORTE, new species. 



Plate 2, figs. 8-10. 



Scolex. — Squarish in front view, bothria cup-shaped, with thick, 

 muscular walls, directed forward. There is an anterior accessory 

 sucker which, in contracted scoleces, is enclosed in the bothrial cup. 

 This condition is brought about by the contraction of a sphincter 

 muscle at the margins of the bothria. The sphincter is much weaker 

 than in O. paidwn. Back of the bothria the scolex contains a com- 

 plex of vessels of the excretory system, together with many strong 

 muscle fibers, which continue into the strobile. There is no trace 

 of a myzorhynchus. 



Strohile. — Unsegmented portion (neck) long, and crossed by fine 

 transverse lines', which make a serrate outline on the lateral margins. 

 In some cases of extreme flaccidity the strobiles become attenuated 

 and lose the serrate character of the margins. The serrations may 

 continue to the posterior end of the strobile. Adult and ripe 

 proglottides do not appear in any of my material. The first indica- 

 tion of segments may be as much as 5 mm. from the scolex, wkere 

 the breadth is many times the length. They gradually increase in 

 length but remain about the same breadth. Toward the posterior 

 end they become squarish, then longer than broad. 



Reprodi(ctive organs. — Only the rudiments of genitalia had de- 

 veloped. Th.e genital pores are irregularly alternate, and a little 



