ZOOLOGY. 



317 



legion of tlie liead becomes much more like what it will be in the adult, 

 while its circlets of cilia begin to disappear ; (C) two distinct legions 

 become apparent in the head, the tentacles become prominent, the walls 

 of the mid-gut are considerably thickened ; and there is still a mass of 

 rounded, indifferent cells, which appear to be the rudiments of the gen- 

 erative products. 



Taking these different stages of development into consideration, Dr. 

 Hatschek indorses the view that Pohjgordius is an Annelid, although it 

 manifests many points in adult structure which are merely embryonic in 

 other forms. Folygordius thus represents what may be designated 

 Archi-Anuelids or primitive Annelids, and its affiliations with the other 

 types are indicated as follows : 



Annelides. 



First order, PolygordiUla'. 

 Second order, Chwtopoda. 



First suborder, Saccocinidce. 



Second suborder, Folycha'ta. 



Third suborder, Oligocluvta. 

 Third order, Birudinea. 

 Fourth order, Gephyrea. 

 (Condensed from J. R. J/. S., vol. ii, pp. oC3-5G7.) 



PLATY HELMINTHES. 



PARASITIC TLANARIANS. 



Inasmuch as extremely few parasitic Plauarians have been hitherto 

 recognized, the discovery by Dr. von Ihering of one which occurs in the 

 kidney of Murex is noteworthy.* The new form has been called GraffiUa 

 muricicola, and is easily perceptible in that organ by its reddish-brown 

 coloration. It attains a length of about 5 millimeters, and is distin- 

 guished by the development of a thick anterior and narrow tail-like 

 posterior region, quite distinctly marked off' from each other. But the 

 most prominent characteristic of Graffilla is the structure of the pharnyx; 

 this is not provided with a special sac or pouch, and in this respect the 

 new form is distinguished from all similar species, and is therefore made 

 not only the type of a distinct family, but a distinct group of Khabdocoila. 

 These it is proposed to di\ide into (1) such as have a pharynx ( Pha- 

 ryngea), and (2) such as are deprived of a pharynx {Apharyngca). To 

 the former group the Graffillidce belong; but, as already indicated, they 

 are differentiated from all the other Pharyngea by the absence of a special 

 pharyngeal pouch, and therefore stand in a section apart from the rest. 



Another parasitic Planarian has been found by Dr. Arnold Lang in 



* Ihering (H. vou). Graffilla muricicola, eiue parasitische Rhabdocoele. Zeihclir. 

 f. Wins. ZooL, vol. xxxiv, pp. 147-174. 



