55 
vagina unites with the male duct. The genital pore lies in the 
median line at the fork of the intestine. The ovary is four-lohed, 
and from it comes a short duct giving off dorsally a large oval 
receptaculum seminis. It then receives the vitellarian duct, and 
curves up as a much winding uterus filled with small and very 
numerous eggs. The vitellaria are formed into a seven-lobed mass 
placed behind the ovary and visible as a conspicuous dark star 
posteriorly. The single duct runs forward to open into the oviduct 
close to where it gives off the receptaculum seminis. 
The life history is unknown. 
Genus — Derogenes. 
Derogenes various (0. F. Miiller). (Plate IV., fig. 4.) Odhner, 
" Fauna Arctica." page 360. 
This is, perhaps, the most universally distributed Trematode 
on this coast, although it does not occur in great numbers in each 
individual. I have found it in the Angler, Grey Gurnard, Ling, 
Long Rough Dab, and Dab. The most usual place in which I have 
found it is in the mouth of the Long Rough Dab, as I have already 
mentioned in a previous paper.* I have generally found it in the 
stomachs of the other fish, and now and then in the intestines. 
Odhner states that about eighteen different fish are known to 
harbour this parasite. Nicoll found it at St. Andrews in the 
stomach, intestine, oral cavity, and oesophagus of various fish, and 
Johnstone found it in the Whiting on the Lancashire coast. It 
is evidently common in many parts. 
This well-known species is easily seen by its bright golden 
yellow colour, due to the numerous eggs. The body is colourless 
and unarmed, but with sometimes an appearance of striation due 
to wrinkling of the skin. My specimens measure on an average 
about 4-5 mm. in length. The largest are from the mouth of the 
Long Rough Dab. The oral sucker measures 0-80 mm. across, and 
the ventral 0-6 mm. The latter is placed behind the centre of the 
body. There is no prepharynx ; the pharynx measures 0-10 mm., 
and leads to a narrow oesophagus branching into two rather broad 
intestinal lobes which reach almost to the posterior end of the 
body. The excretory system consists of a narrow posterior stem 
branching just behind the ventral sucker, and running up to join 
dorsal to the oesophagus. The testes are globular, one each side 
of the ventral sucker, one, the left, usually in front of the other 
Trematodes of the Northumberland Coast, No. II." Op. cit, page 16. 
