744 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
and six smaller vessels which are much looped and anastomose consider- 
ably ; it may he made out without the aid of sections by simply 
compressing an uninjured specimen. 
The generative orifices lie at the sides and are (irregularly) 
alternately right and left. The testes are large multicellular organs 
which lie to the inside of the vitellaria ; there are about twenty-five in 
each proglottid ; the seminal vesicle is a large organ which is formed by a 
looped and coiled continuation of the greatly widened trunk of the vas 
deferens. The cirrus-sheath is spindle-shaped and its wall is formed by 
a layer of longitudinal and one of circular muscles ; when the cirrus is 
protruded the space between it and the sheath is filled by loose connective 
tissue. 
The two ovaries lie at the hinder margin of the proglottid and 
contain germ-cells *013 mm. in diameter; the efferent ducts lie on the 
inner side, opposite one another, and lead to the ootyp ; the vitellaria 
occupy almost the whole of the outer side of the proglottids. The 
various efferent ducts unite at the hinder end of the vitellaria into 
a common yolk duct. In the form and position of their vitellaria the 
Fish-Taeniae differ considerably from those of Mammals aud approach 
those of the Paramecotyleae on the one side, and many Trematoda on the 
other. In describing these various organs the author makes com- 
parisons with those of other Fish-Taeniae which have been already 
described. 
The larva, like that of Triaenophorus nodulosus, is encysted in the 
liver of the fish, whose intestine harbours the adult Taenia ; in the matter 
of development, therefore, there is again a marked difference from that 
of the Taeniae of warm-blooded animals, and a resemblance to that of many 
Paramecotyleae. 
Development of some Taenise of Birds. * — Herr A. Mrazek has 
investigated the cysticerci found in various freshwater Crustacea, and 
limited his further studies to such as are found in their cestoid condition 
in the duck and goose. Taenia fasciata of Anser cinereus and A. albifrons 
passes its cysticercoid stage in Cyclops agilis ; the long diameter of the 
intermediate form is from *18 to *22 mm., there are eight hooks from 
•055 to *068 mm. in length, and the caudal appendage is extremely long. 
The cysticercus of Taenia tenuirostris, which is remarkably small and has a 
crown of ten hooks, is found in Cyclops viridis, C. agilis , and C. lucidulus ; 
the tapeworm hosts are Anser albifrons , Anas boschas and A. acuta , 
Fuligula cristata and F. brasiliensis. Although the cysticercus of T. gracilis 
was first described by Linstow from the intestine of the perch, it is 
also found in Cypris compressa and C. viridis; the adult hosts are 
Anas bosclias and A. acuta and Mergus merganser. A few cysticercoids 
of T. analina have been taken from Cypris incongruens , and one from 
C. compressa ; the hosts of the adult are Anas boschas and A. acuta. A 
new Cysticercoid form, which the author calls Cysticercus Hamanni , was 
found in Garmmarus pulex, but the cestoid form and its host are still 
unknown. The body of the young parasite is from *30 to *40 mm. 
long ; the greater part of the body is covered by fine cilia which are de- 
scribed as being immobile; the crown contains from 18 to 22 hooks. 
* SB. Iv. Bulun. Ges. Wits. Prag, 1891, pp. 97-131 (2 pis.). 
