392 DISCOVERY REPORTS 



the anterior portion of the body the bundles are arranged very densely. They seem to form definitely 

 shaped bundles in the mature and gravid segments. In the young specimens their arrangement is 

 radiate. The differences in the arrangement of the longitudinal muscles in the various segments are 

 shown in Figs. 34-6. The circular muscles are well developed. 



The testes are numerous and arranged in many layers. They measure about x 68(53-60)^ in 

 transverse section and about 45 - 53^ in horizontal section. The vas deferens is well developed and 

 arranged in coils. The cirrus-sac is about 135 /x long and about 60 /j, wide. 



The fairly large ovary is composed of large egg-cells. The uterus, filled with eggs, occupies most of 

 the medullary parenchyma. The eggs, after the uterus has broken through the cuticle, are discharged 

 by numerous pores situated in the dorsal part of the segment. No specially defined uterine pore is 

 present, as in the species of Tetrabothrius described above. There is no difference in the formation of 

 the uterine ducts, but instead of one, several openings are formed. Figs. 37-39 show the mode of dis- 

 charging the eggs. 



The egg is about (83-99 :< 66)/u, and contains the embryo, 33x50^ in diameter. The embryonic 

 hooks are about ij/j. in length. 



The excretory system is well marked. 



Genus Diplogonoporus Loennberg, 1892 



Diplogonoporus balaenopterae Loennberg, 1892. (Figs. 42-43; PL XXI, figs. 5-7.) 



Hosts: Blue Whale (Balaenoptera musculus); Fin Whale (B. physalus); Sei Whale (B. borealis). 

 Locality: South Georgia. 



The body is flat and tape-like. In all the specimens with a scolex, irrespective of size, the anterior 

 part of the body is undulate, as shown in PI. XXI, fig. 6. Though this modification of the body may be 

 caused by fixation, it seems nevertheless to be constant. Although the only complete worms occurring 



Figs. 42, 43. Diplogonoporus balaenopterae from Sei Whale. 42, scolex; 43, transverse section showing 



arrangement of longitudinal muscles. 



in the collection measure up to about 13 cm. in length, there are many fragments, one of which is over 

 8 m. long. The scolex is typical, with two grooves from 1 to 1-5 mm. broad and from 1 to 2 mm. long. 

 The bothria are deep and well pronounced. There is no neck. 



The longitudinal muscles, as examined in transverse section, form irregular groups of muscle 

 bundles composed of loosely arranged fibres. Individual groups are separated by muscle fibres, run- 

 ning dorso-ventrally. The circular muscles are well developed. 



