Astacilla longkornis. 8 1 



When at rest, the Astacilla clasps 15 



hold of any object in the water 

 by its creeping legs; and, when 

 alarmed, it bends itself at the tail 

 and erects all the body anterior 

 to this, having the antennae folded 

 under the belly more or less. In this rather grotesque atti- 

 tude it resembles many caterpillars. 



I have mentioned (VIII. 496.) that the ova are produced in 

 the large barrel-like middle segment, which is true ; but the 

 animal is not oviparous, as my remarks might lead any reader 

 to infer. The eggs are hatched within this uterine cavity, so 

 that the animal is ovo-viviparous. The young, while yet in 

 the uterus, are about the eighth of an inch long, and have a 

 general resemblance to their parent; but the differences are 

 remarkable enough, and are as follow: — 1st, There is no 

 marked disproportion in the size of the segments, and the 

 middle segment was not to be distinguished from the others. 

 2dly, The young were smooth every where : ciliae could be 

 detected neither on what were presumed to be the anterior 

 legs, nor on the caudal processes; neither were claws visible. 

 3dly, The number of pairs of legs, or leg-like organs, was ex- 

 traordinary. Besides what were conjectured to be the rudi- 

 ments of the anterior legs, there were four pairs of long fila- 

 ments, jointed like legs; and behind these, separated by a 

 short space, were other two pairs of similar ones : these were 

 followed by three pairs of shorter legs, and at the tail there 

 were numerous appendages, apparently of two kinds, but their 

 number and shape could not be well made out. 4thly, The 

 head and superior antennae were larger in proportion than 

 they are in the adult ; but, in the general contour of the body, 

 there was no great dissimilitude between the young and ma- 

 ture individuals. The figure appended to this notice was 

 drawn with care, but the softness of the specimens, which 

 were dead and had been macerated in fresh water for a few 

 hours, prevented them being displayed in such a manner as 

 would have allowed the details to be given more fully and 

 accurately. Such as it is, your readers will see, by a com- 

 parison of it with the figures in VIII. 495., the nature of the 

 metamorphosis which the animal undergoes in its progress to 

 maturity. 



Chondraca'nthus Lo v phii. (Jig. 16.) 



Animal milkwhite, soft, opake, the body half an inch long, 

 two tenths broad, the caudal filaments rather more than 2 in. 

 long. Head tolerably distinct, convex dorsally, with two 

 round eminences on the crown, and a narrow mesial groove 

 running forwards to a small marginal sinus, semicircular in 



