536 THE ANATOMY OF INVERTEBRATED ANIMALS. 



oesophagus. From each of these a relatively stout longitudi- 

 nal cord proceeds, overlying the bases of the feet (and hence 

 widely separated from its fellow), to the posterior extremity 

 of the body. As Grube has stated, there are no distinct 

 ganglia on this cord. On the contrary, ganglionic cells ap- 

 pear to be pretty evenly distributed along its ventral face, 

 throughout its length ; and nerves, which pass transversely 

 outward and inward, are given off from opposite sides of it 

 at short intervals. Grube has shown that many of the 

 branches that take the latter direction are commissures be- 

 tween the two cords. 



The muscles of Peripcitus are not striated, which is a 

 curious exception to its generally well-marked arthropod char- 

 acteristics. 



Mr. Moseley has proved that the sexes are distinct. The 

 ovary is small, divided by a median septum into two lobes, 

 and lies beneath the alimentary canal. The oviduct, at first 

 single, divides into two branches, which are long, and, pos- 

 teriorly, present uterine dilatations. They then unite, and ter- 

 minate by a short vagina on the ventral aspect of the rectum. 

 The testes are ovate bodies, each with a cascal appendage. 

 The lonof and coiled vasa deferentia unite into a common 

 duct, which opens in the same position as in the female. The 

 ova are developed within the uterine dilatations of the ovi- 

 ducts.* 



Mr. Moseley has made out the chief points in the develop- 

 mental history of Perii^atus. 



In an early condition, the embr3'o is very like that of a 

 Scorpion, but is folded upon itself, so that the ventral aspects 

 of the anterior and posterior halves of the body are turned 

 toward one another. As in the Scorpion, there is a pair of 

 large procephalic lobes, succeeded by a series of segments, 

 from the sides of which, processes — the rudiments of the 

 limbs — bud out. The procephalic lobes give rise to a kind 

 of hood, the lateral angles of which extend over the bases of 

 the first pair of limbs, and join with those of the second pair, 

 which are the oral papilla? of the adult. The first pair of 

 limbs thus become inclosed within the hood (tlie margins of 

 which form the suctorial lip of the adult), and developing 

 two chitinous claws uoon their extremities, like those of the 



' One of tlao specimens wliicb I examined was a precrnant female, but the 

 viscera were glued together, apparently by the action of the spirit in which it 

 had been preserved, in such a manner, that little could be made of their struc- 

 ture or of that of the embryos. 



