NOTE ON THE HABITAT AND STRUCTURE 
OE GBASSICAUDA [NEMATODA]. 
By H. A. BAYL1S, M.A., D.Sc. 
I 
(Published by permission of the Trustees of the British Museum.) 
(With 3 Text-figures.) 
Complete; specimens of this nematode are difficult to obtain, owing to the 
manner in which the worms bury themselves in the tissues of the urinogenital 
system of the Cetacea in which they are found. Mr A. G. Bennett, to whom 
the writer has previously been indebted on more than one occasion for 
Crassicauda material, has recently sent home further interesting specimens 
from South Georgia, accompanied by notes and a sketch which throw some 
light upon the burrowing habits of the worm. A special effort was made to 
obtain complete specimens by dissection. 
In a previous note, in which an attempt was made to collect the lecoids 
of the occurrence of this remarkable genus, the writer (1916) quoted an inter¬ 
esting passage from a report by Mr J. B. Hamilton, on the foimation of 
“connective tissue masses” by the worms in the kidneys of Balaenoptera 
physalus. From Mr Bennett’s observations it appears that “masses” or 
nodules of a similar nature may also be formed in other tissues. I he ac¬ 
companying diagram, which is adapted from Mr Bennett’s drawing, shows 
the course taken by one of the worms in the tissues of the penis of a Balaeno- 
ptera (probably B. physalus). The caudal end of the worm hangs freely in 
the lumen of the urethra, through a perforation in the wall of which its body 
passes into the dense surrounding tissue. Through the kindness of Mr R. H. 
Burne, the writer has been enabled to compare Mr Bennett s sketch with a 
preparation of the penis of a Balaenoptera in the Museum of the Roy al C ollegc 
of Surgeons. This makes it clear that the actual tissue invaded by the parasite 
is the dense fibrous sheath of the corpus cavernosum. 
According to Mr Bennett’s notes, the free portion of the worms vaiied 
from two to four inches in length. After traversing the fibrous tissue for 
some distance, the body passes into a dense nodule (A), where it becomes 
flattened and much coiled. The substance surrounding the worm in this 
nodule is in some cases putty-like, in others hard and apparently calcareous. 
The worm may be traced on again beyond this nodule for a longer or shorter 
distance, but eventually it passes into a second nodule (B) ol pus and fibrous 
