210 Transactions of the 



II. — On Agchisteus plumosus (Parjitt). By E. Parfitt. 



{Read hefore the Koyal Microscopical Society, April 2, 1873.) 



Plate XV. (Upper portion). 



The accompanying sketch is one of a very remarkable animal I 

 met with in the mucous matter surrounding Hsematococcus hinalis 

 (Hassell). I do not remember to have seen anything before like 

 this. At first sight it has something of the appearance of a large 

 rotifer, being transparent, white, and showing very clearly the pale 

 yellowish stomach or intestine; as this vessel seems to combine 

 both, the contraction would appear to divide the stomach from the 

 intestine proper, although I did not observe any valve separating 

 or dividing the two ; but I presume the siphon-like bend and con- 

 traction would perhaps answer the purpose to an animal like this. 



This creature is provided with a double coating, an ectoderm 

 and an endoderm ; the outer is wrinkled into transverse folds, with 

 many small protuberances arising therefrom ; out of each of these 

 springs a beautiful plumose bristle or spine ; by the side of each of 

 these springs a short spine, bearing at its apex a number of fine 

 bristles, reminding one of a little aspergillifbrm brush. On the 

 anterior part of the body and placed somewhat laterally are six 

 bundles of simple slightly-curved spines or spinetts; and below 

 these, on the posterior half of the body, are five rather long slightly- 

 curved furcate spines directed backwards. 



The oral aperture is lateral and inferior. This creature pro- 

 gresses by contracting its body, and with the assistance of the 

 spines very similar to the progress of an Annelid. I could not 

 discover any rings or annulations, the nearest approach to this is 

 the folds of the dermal coat. 



Viewing this animal as a whole, it is from the form and disposi- 

 tion of the spines very closely related to the Annelids, but at what 

 position to approach this group to connect them I do not see my 

 way clear except through Chatogaster. On the other hand, the 

 simplicity of its interior organization seems to prevent a very close 

 alliance. Although the general appearance is that of a large rotifer, 

 and which by some are considered to approach very closely, if not 

 quite, to connect the Eotifera with the Annelids, this creature does 

 not quite fill the requirements of that position to connect them at 

 this point ; the position of its mouth and the simplicity of its in- 

 ternal organization precludes it. At the same time I think there 

 can be little doubt but that its nearest allies are the Annelids. I 

 have named it provisionally Agchisteus plumosus, presuming it to 

 be next of kin to the Annelids, and plumosus from the beautiful 

 plumous spines. 



I can say nothing as to its habits, except the finding of it in the 



