140 THE VICTORIAN NATURALIST. 



first noted in snails from the pool near the bridge at Heidelberg. 

 Isidora (Btdiniis) tenuistriata, Sowerby, gave embryos closely 

 agreeing with the typical form as figured by Professor Thomas in 

 the Q.J.M.S, xxiii., 1883, all stages being met with except the 

 free-swimming embryo and cyst. The same applies to embryos 

 found in Ancylus Tasmanicus, Ten. Woods, a limpet-like form of 

 very minute size. 



Living side by side in this pool are species of two genera of 

 minute snails very similar in outer form, viz., Segmentina and 

 Planorbis. These have been identified as Segmentina Victorice, 

 Smith, and Planorbis Gilberti, Danker. In the former fluke-cysts 

 were found, one of which was noted to contain an embryo pro- 

 vided with a circlet of spines in the region of the anterior sucker. 

 Further observations will probably reveal the presence of other 

 embryos of this form. The Planorbis (sp.) furnished flukes in 

 sporocyst, redia, and cercaria stages. Three specimens gave 

 cercarise with very distinct pigment spots close to the anterior 

 sucker, whilst three others produced a forked-tailed variety out of 

 sac-like structures much larger than the ordinary redire. Want of 

 material, unfortunately, did not allow of extended observations of 

 these curiously modified forms. 



Another pond at Heidelberg gave a large supply of Isidora 

 (Bidinus) gibbosa, Gould, var. fusi/ormis, Nelson and Taylor, 

 which yielded a distinct variety of cercaria, furnished with a very 

 definite spine or stylet springing from the anterior sucker, minute 

 spines also clothing the anterior part of the embryo. The 

 cercarise seem to be produced from a sac-like form like a sporo- 

 cyst, no rediae having been observed. Further attention, however, 

 will be given to this point. Cysts were frequently met with in 

 the shell. 



The north-eastern parts of the colony have furnished two new 

 intermediate hosts in the snails Isidora (Bulinus) texturata, 

 Sowerby (the form referred to last month as Bulinus inflatus), 

 and Limncea lessoni, Deshages, which gave embryos in all stages 

 of development up to and including encystment, the embryos 

 also in these cases giving different characteristics. 



It is not suggested that all the embryo fluke forms alluded to 

 above are those of Fasciola hepatica, which reaches its mature 

 state in the sheep Several of them are, doubtless, the embryo 

 stages of flukes which come to maturity in fish or frog or bird. 

 Indeed Planorbis marginatus has been reported as harbouring 

 embryos of Distomum lanceolatum, and Cercaria ephemera, an 

 embryonic form of Monostoimun Jlavum, also makes its home in a 

 species of Planorbis. The form, however, which agrees with that 

 described by Professor Thomas is most probably the sheep fluke, 

 and it has without doubt been seen in different species of the 

 genera Ancylus, Isidora (Bulinus), and Limncea. 



