8 4 



HA RD WICKE'S SCIENCE- G OS SIP. 



bulla differs considerably both in the mallei and incus. 

 The most serious objection however to incorporating 

 Monostyla with Euchlanis is that in that genus the 

 foot is said to be "simple, styliform." On this 

 point Pritchard says, "Owing to the almost constant 

 vibration of the foot-like tail, it is difficult to observe 

 the true form of its termination, the motion producing 

 an optical illusion ; hence it appears double, though 

 in reality single." In spite of this warning, I believe 

 that the tail-foot of my M. bulla was a furcate one, 

 although I may be mistaken. Further information 

 on this point is much to be desired, and microscopists 

 having the opportunity would do good service by 

 working out this problem. In the genus Euchlanis 

 the lorica is more or less depressed, and in some 

 species is very diaphanous. Ehrenberg described it 

 as being "slit inferiorly," and Pritchard figures 

 E. dilatata as being quite open on the ventral surface. 

 Cohn was the first to point out that the Danish natu- 

 ralist was mistaken in this, and my own experience 



have not been able clearly to distinguish the margins 

 of the two plates, owing to their thinness and trans- 

 parency ; indeed, this is often only made out by the 

 careful and prolonged observation of numerous indi- 

 viduals. From a drawing and description I sent to 

 Dr. Hudson, he was inclined to consider it as probably 

 Jllouostyla cornuta ; but that its tail-foot is a furcate 

 one I have not the slightest doubt. This fact, and 

 the further one of its dorsal and ventral plates being 

 separated, place it in the genus Euchlanis ; possibly 

 it may be E. Hornemanm ', though the description of 

 that species in " Pritchard " is too meagre for me to- 

 feel very certain. Fig. 57 a : animal retracted, and 

 showing its projection beyond the margin of dorsal 

 and ventral plates; Fig. 57 b : animal exserted, and 

 showing trochal wreath and longitudinal muscles. 



Another Rotifer, slightly larger than the last, and 

 evidently belonging to the same genus, is shown in 

 Fig. 58, a and b. In this the lorica is somewhat broader 

 than in the last species, and is truncated anteriorly. 



Fig. 57«. — Animal retracted. 



Fig. 57^. — Animal exserted. 



Fig. 58^. — Dorsal view. 

 Animal retracted. 



Fig. 585. — Side view. 

 Animal retracted. 



confirms his. In a letter to me Dr. Hudson says : 

 " No Euchlanis I have ever seen has a cleft-ventral 

 surface to its lorica ; in all cases the lorica consists, as 

 you state, of an upper and lower plate, with a furrow 

 between them, this apparently open groove being 

 closed by a flexible membrane." The dorsal plate, 

 in nearly all the species I have come across, is larger 

 than the ventral, and is generally much more convex. 

 It will be unnecessary for me to describe the two 

 large handsome species, E. triquetra and E. dilatata, 

 as they are fully described and figured in most works 

 devoted to this subject. I have however come 

 across four forms, which will not be so familiar to 

 microscopists, and of which they may be glad to have 

 figures and description. Fig. 57, a and b : this is a 

 small Rotifer I have frequently been able to procure 

 from a shady well in our neighbourhood. The lorica 

 is ovate and excised in an angular manner in front, 

 and there are four, either ridges or slits, on the back. 

 Of the two plates, the dorsal one is the largest, and 

 it is arched, while the ventral one is almost fiat. I 



Its foot is very short, so as not to project beyond the 

 lorica, but the toes are long. Fig. 58 a, dorsal view, 

 animal retracted ; Fig. 58 b, side-view, animal re- 

 tracted, showing the large arched dorsal plate cover- 

 ing the sides, and the small ventral one. In Fig. 59, 

 a and b, is shown a Rotifer with many points of resem- 

 blance to the last. Like that species, it has a depressed 

 lorica, broadly ovate, truncated anteriorly ; but differ- 

 ing from it in having two anterior spines, and in the 

 toes being somewhat shorter. It frequently remains 

 retracted for considerable periods, but when it does- 

 extend itself it shows remarkable activity. It is not 

 very transparent, being generally, but not invariably, 

 of a brown colour. Fig. 59 a, dorsal view, animal 

 retracted ; Fig. 59 b, side view, animal exserted, and 

 showing the considerable interval separating the two 

 plates. It may possibly be Pritchard's E. hippo- 

 sidcros, but in my specimens the foot was not " armed 

 with one pair of bristles," neither was the space 

 between the plates exactly of the character indicated 

 by its specific name. In all the above rotifers there 



