MisceUaneous. 151 



canals bifurcate aiiJ uiiile wltli each other by the brauches thus 

 formed ; at this point these vessels emit numerous branches, which 

 ramify upon the inferior sui'face of the disk and tlow into a double 

 circular vessel which runs along the margin of this disk. 



Besides these lateral vessels, the circulatory apparatus includes a 

 median ventral vessel envelopiug the nervous sjstem. At the ante- 

 rior part this vessel gives origin to a ring, the ramifications of wliicli 

 unite with those proceeding from the two superior lateral vessels ; 

 at the hinder part this ventral vessel passes above the canals which 

 unite the lateral vessels, and gives origin to numerous ramifications 

 whicli open into the circular vessels of the margin of the disk. 



Nervous si/stem.— The nervous system, whieli is very like that of 

 Clqjaine, besides the cerebrum and the posterior mass, consists of 

 eighteen ganglia, each formed of two pairs of largo lateral vesicles, 

 and two rather smaller ventral vesicles j^laced one behind the other. 

 Each ganglion emits on each side a single nerve, which shows itself 

 further on. 



The eyes, two in number, are very large, of an orange colour and 

 cup-like shape. 



The integuments, especially in the anterior part, are very rich in 

 large glandular cells with granular contents. 



The very peculiar arrangement of the circulatory and digestive 

 a])paratus, as we have just described them, appear to us to combine 

 a set of characters sufficient to authori/e the formatioi; not only of 

 a genus but also of a family. This family, the position of which 

 seems to be indicated in the neighbourhood of the Rhynehobdellida;, 

 we shall designate by the name of JiOphobdellidae, derived from the 

 word Lophohddla (from Ao^os, a tuft, and ftSiWu, a leech), which 

 we propose as the name of the genus. Ihe species from Sene- 

 ganibia and the African rivers may bo inscribed under the name of 

 Lophobdella Quatrcfcu/esi. — Comptes liendm, June 30, 1884, p. loOT. 



On a new Tj/pe of Ela.ttic Tissue observed in tht Larva of Eristalis. 



B)' M. H. YlALLANES. 



There are few naturalists who have not had occasion to observe 

 tlio singular movements of the respiratory tube which terminates 

 the body of the larva? of Eristalis. This tube, which is composed, 

 like a telescope, of cylindeis fitted one into the olhei', can, at the 

 pleasure of the animal, be greatly shortened or lengthened to seek 

 the air at the surface of the water. The elongation of the respi- 

 ratory tube is effected by means of the contractions of the body, 

 which drive the cavitary liquid into it. Its shortening is produced 

 by special muscles and by elastic bands lodged in its interior. 



It is to the structure of these latter parts, which, at least so far 

 as I know, have not been investigated, that 1 wish now to call 

 attention. Each of these elastic bands is a single cell, but con- 

 structed in such a way as to perform the part of a thread of india- 

 rubber. One of these elements, examined in a half- retracted state 

 and in the blood of the animal, presents the following characters: — 

 its cell-bod V is fusiform ; one of its extremities is attached to the 



