352 
Entozoa of Fishes 
into numerous convolutions. Beginning on the inner side of the ovary 
it passes backwards towards the right testis then turns and winds round 
the outer side of the ovary. Within the arc formed by the yolk-glands 
it makes a number of intertwining loops. It then passes round the left 
testis and so towards the genital sinus. This arrangement is almost 
peculiar to the species. The uterus is for the most part in front of the 
pharynx but it does not extend in front of the yolk-glands. The ova 
are numerous and of regular broad oval shape. They measure 0026 — 
0 031 mm. in length and 0 - 016—0'020 mm. in breadth, the average being 
0’0285 x R0185 mm. 
Species 2. Prosorhynchus crucibulum (Rud. 1819). 
This is the second and larger of the two Gasterostomes, which are 
harboured by the conger. Like P. aculeatus it occurs in no other host. 
It was met with only half as frequently but it is probably quite as 
common as the other species. 
Hitherto, although encountered by a number of observers, the 
species has not been correctly described. Originally described by 
Rudolphi as a Monostomum, it was redescribed by Molin (1858 and 
1861) as a new species of Gasterostome. Rudolphi’s description was 
recognised and amplified by Olsson (1876) who, however, curiously 
euough, failed to see that it was identical with Molin’s species. With 
the latter he confused P. squamatus and P. aculeatus. Odhner (1904) 
disentangled this confusion and succeeded in defining the three species 
fairly accurately. His diagnosis of P. crucibulum, however, based as it was 
on rather scanty material, is the least satisfactory of the three, and does 
not give an adequate idea of the form. Strictly speaking it is incorrect. 
My material consists of about a dozen adult specimens from the 
Clyde and a large number of immature and a few adult specimens from 
the South coast. The length of adult individuals is 2—3‘7 mm. Egg 
production does not occur under 2 mm. Molin gives the length as 
4—6 mm. Odhner’s size-limits (T75—2 - 25 mm.) are, therefore, much 
too restricted. 
The shape of the body is different from that of P. aculeatus ; it is 
elongated, squarely cut at the anterior end and pointed posteriorly. It 
is slightly flattened and the greatest breadth (about |ths of the 
length) occurs near the middle. An average mature specimen measures 
3T5 x IT mm. 
