the Genus ( 'lasHicaiida. 411 



blue wliale (^Bahvnoptera musculus), and tlie worms were 

 found with their caudal ends hanging freely inio the urinary 

 ])assage. In one case portions of the host's tissues (penis) 

 were forwarded, and shoAV the head-ends of the worms still 

 deeply embedded. The tissue being very firm and muscular, 

 and having been hardened in formalin, it has proved im- 

 ]>ossible, as is usually the case, to extract the worms intact. 

 They pursue a very tortuous course in the tissues, and are 

 easily broken in the attempt to remove them. The present 

 account, therefore, will necessarily be confined to the cha- 

 racters of the posterior end. 



In a former paj)er (1916) the writer described what was 

 believed to be the head of an example of Crasdcauda crassi- 

 cauJa (Crepl.). Up to that time there was no definite ground 

 for believing that the genus included more than one species. 

 In view, however, of certain con.siderations now to be set 

 forth, there seems to be good reason for suspecting that two, 

 and perhaps three, species of Grassicauda occur in whales. 



The original worms described by Creplin (1829) as Filaria 

 crassicduda were comparatively small, 6^ inches being given 

 as the length of a complete male, 12 to Id inches as that of a 

 com[)lete female. Creplin describes and figures a single 

 si)icule in the male. Tlie greatest thickness (and this in one 

 exceptionally thick female) was about 1 line [ = about2 nnn.]. 



Leiper and Aikinson (1915), reporting on material con- 

 tained in the 'Terra Nova' collection, which they had 

 previously (1914) referred to C. crassicauda (making this the 

 type of the new genus), remark that they were unable to find 

 any spicules in the males, and conclude that they are absent. 

 They also state that the material (which consisted only of 

 lieadless fragments) included portions of both males and 

 femalis of a length of 1 G inches. 



A re-examination of the 'Terra Nova' material, now in the 

 British Museum' and its comparison with the )iew material 

 from the Scmth Shetlamls, lead me to believe that the latter 

 represents the true C. crassicauda, while Leiper and Atkinson's 

 determination of the former as belonging to Creplin's sj>ecies 

 was erroneous. It is proposed, therefore, to regard the 

 'Terra Nova' specimens as representing a new and larger 

 species, which may be named Crassicauda hoopis. It attains 

 a thickness of between 8 and 4 mm. Leiper and Atkinson 

 uniortunately gave no figures of the worm. Figures of both 

 forms are therefore given here for comparison. 



The material sent by Mr. Bennett includes fragments 

 nnasuring up to about lo".5 cm. [ = <'»^ inches] in length 

 and not more than 2 mm. in thickness, 'ihc males have a 



2«* 



