140 GOSSE, ON DYSTERIA. 



3. The excavation in the interior part of the head causes 

 the part above it to assume the form of a hook^ the point of 

 which is downwards and forwards. 



Now in the Coluridce, as well as in some other allied 

 genera, a broad frontal hook is very characteristic. It is 

 true, that in these it is apparently articulated to the lorica, 

 of which it forms a firm appendage, and is endowed with 

 separate motion. In Stephanops, however, it is fixed and 

 immoveable. 



From these slight analogies we may perhaps link the fonn 

 with Colurus and its allies. 



But the predominance of resemblances is with another 

 group, — that which includes Monocerca and Mastigocerca ; 

 and some of these points of similarity are the more in- 

 teresting, because they are such as already isolate (though in 

 a much less conspicuous manner) these genera from the 

 more normal Rotifera. 



1. They are single-toed; whereas the majority of footed 

 Rotifera are two-toed. 



2. Some of them are unsymmetrical ; as Mastigocerca, in 

 which the dorsal carina leans over to the right side, and the 

 left series of manducatory organs is more developed than the 

 right ; and Monocerca, in which the right malleus is wanting, 

 and (in some species) the antennal processes and the frontal 

 spines are unequally developed. 



3. The manducatory apparatus is of far greater com- 

 parative length in these genera than in any other known 

 Rotifera ; in Monocerca porcellus and M, stylata approaching, 

 and in Mastigocerca carinata, equalling, half the length of the 

 lorica. 



4. These genera, when crawling on a smooth surface (as a 

 plate of glass), are able to render themselves stationary, and 

 acquire appoint d'appui for their progression, by the curious 

 provision of a thick glutinous fluid. This is secreted in the 

 hinder region of the body, and thrown out in a copious 

 stream, which may be often seen passing downi the long foot 

 like a thick ent^vining cord, and then left trailing behind, as 

 the animal moves forward. Now this interesting contrivance 

 is paralleled in the new form we are considering ; for Mr. 

 Dyster tells me that the point of the foot remains glued to 

 the glass after death, " probably from some exudation." 



From these analogies, I incline to give to this animal a 

 place in the family Monocercadce, as a very aberrant genus. 

 I consider that it has remote relations also with the SaJpinadoi, 

 and especially with the Coluridce (through Monura) ; and 

 that it is an annectant form between the Rotifera and the 



