W. Nicoll 
25 
measure about 0-060-0-063 x 0-034-0-039 mm. They are provided 
with a small knob at the anopercular pole. 
This species presents an undoubted affinity with the Allocreadiidae 
but the structure of the prepharynx and the presence of pigment spots 
mark it out as a distinct type. 
Genus Coitocoecum n. g. 
Coitocoecum. gymnophallum n. sp. 
(Plate IV, fig. 2.) 
About half a dozen specimens of another somewhat remarkable 
parasite were obtained from the intestine of a black bream {Spams 
australis). It is a small, plump, elongated oval species with rather 
pointed ends, and it has a distinct lemon-yellow colour. 
Although they may reach a length of 3 mm., most of the specimens 
are considerably smaller. The following measurements are taken from 
the largest specimen. The breadth, which is fairly uniform, reaches 
a maximum of a little more than one-third of the length. There are 
no cuticular spines. 
The sub-terminal oral sucker is somewhat transverse and measures 
0-27 X 0-31 mm. The ventral sucker is decidedly transverse and 
measures 0-43 x 0-57 mm. It is situated three-eighths of the body 
length from the anterior end. 
There is a well-marked prepharynx, 0-1 mm. in length, a fairly large 
pharynx, 0-21 mm. in diameter, and a short oesophagus about 0-06 mm. 
long. The diverticula are of medium width and fairly uniform. They 
extend along the sides of the body to near the posterior end, where they 
unite in a rounded arch. This condition resembles that in the Cyclocoelid 
Monostomes but is extremely rare amongst the Distomata. It is the 
more remarkable in consideration of the fact that the species in other 
respects is closely allied to the Allocreadiidae. It presents an 
analogous case to that of Genarches and Derogenes. 
The excretory vesicle is a short straight tube terminating just behind 
the ovary. 
The genital aperture is situated near the left side of the middle of 
the pharynx. There is no true cirrus-pouch. The large simple vesicula 
seminahs lies immediately in front of the ventral sucker. There are 
a few prostatic cells but no definite pars prostatica. The ductus is 
moderately long. The testes lie in the posterior third of the body, the 
post-^-esticular space being a little more than one-fifth of the body 
