ON SOME QUEENSLAND THEMATODES. 
379 
to me to be identical with Biauii’s Monostornum pandum 
( 9 , p. 48) on the followiDg grounds : 
Professor Braun had at his disposal only a single specimen, 
which was mounted whole. As the worm is fairly thick and 
dense, it is, of course, impossible to view its anatomy com- 
pletely in a single specimen. 
As far as Brauids description goes my whole mounts 
agree with it very well, the differences being of such minor 
importance as to make it out of the question, in my opinion, 
to propose a separate species for my specimens. A study of 
serial sections, however, not only makes clear important points 
in the animal’s structure that are quite impossible to see in 
the whole mounts, but also shows some of the appearances 
in the latter to be somewhat misleading. While the worm is 
undoubtedly one of the Pronocephalidae Lss. ( 33 ), it does 
not fit into any of the genera at present established, so that I 
am obliged to propose a new genus for it, adding yet another to 
the list of genera containing* only a single species in this family. 
Four of the worms available to me for study I cut into 
sections, one transverse, one sagittal, and two horizontal 
longitudinal. With the help of these series I shall supple- 
ment Braun’s description ( 9 , pp. 48-50), afterwards giving a 
diagnosis of the genus Diaschistorchis, and a discussion 
of its relationships. 
External Characters. — My specimens were all a little 
smaller than Braun’s, varying in length from 8 to 9 mm., 
while being 2*5 mm. broad at the level of the cirrus sac and 
3 mm. broad at the widest part, near the posterior end. The 
form of body is skiff-like, rounded at both ends, rather 
narrower in front, and gradually increasing in breadth to 
near the posterior end. The collar is less conspicuous than 
in the other members of the family, taking the form of a low 
kidney-shaped elevation of the surface of the body round the 
sucker on the dorsal side, but not produced into lobes or 
processes of any kind at its ventro-lateral ends. The dorsal 
surface of the worm is arched, both from side to side and, to 
a certain extent, antero-posteriorly ; the ventral surface is 
