290 ERNEST WARREN. 



tened nuclei are formed ; tliese will be converted into the 

 musculature of the body-wall (Fig. XV, m. c). 



The embryo, which may be regarded as a fully developed, 

 tailless, encysted cercaria, bursts out of its cyst by straighten- 

 ing itself from its bent position. It now leaves its cyst and 

 burrows betAveen the muscle-fibres of its host. In this position 

 it rapidly grows and soon becomes surrounded by a cyst-wall, 

 which stretches as the animal grows, and is constantly being 

 added to by the addition of fresh matter from the bladder. 



Systematic Position. — The enormous genus Distomum 

 has been recently split up by Looss into numerous sub-families 

 and genera. According to this author's system D. cirri- 

 gerum would appear to belong to the sub-family Lepodcr- 

 matinae, and is not very far removed from the genus Astia. 

 The characteristic points given by Looss for the sub-family 

 LepodermatinuB are — the presence of scales; the excretory 

 bladder lies behind the shell-gland ; copulatory organs are 

 well developed ; the testes lie in the middle of the hinder 

 portion of the body ; the ovary lies close to the blind end of 

 the cirrus-sac ; the convolutions of the uterus are sometimes not 

 very numerous, and then they lie wholly in front of the testes. 



D. cirrigerum agrees with these general characters. 

 It also resembles Astia in the great length of the oeso- 

 phagus, but it diifers from it in a number of ways : the 

 excretory bladder is rounded, and is not forked as in Astia ; 

 but in the embryo we have seen that it is obviously V-shaped ; 

 the uterus is relatively short, and lies in front of the testes ; 

 the receptaculum seminis is well developed ; the yolk-glands 

 extend beyond the gut-ca?ca to the posterior end of the body. 



Looss mentions that he finds dark granules in the excretory 

 bladder of Astia; it would be interesting to know whether 

 they are fatty in nature and are similar to those which have 

 just been described in the excretory cells of D. cirrigerum. 



On account of the many important differences D. cirri- 

 gerum could not conveniently be placed in the genus Astia, 

 and I would suggest that it should be placed in Looss's 

 system under the name A stacotrema cirrigerum (v. Baer). 



