M. A. Giavd on the Genus Entoniscus. 139 



alone has appeared to me to be attacked. On the side of the 

 stomach, at the point where the liver is situated, one sees a 

 very voluminous mass, of a more or less yellowish or leaden 

 colour, according to the degree of its maturity, occupying the 

 place of the ovarian branch of the crab. This body pushes 

 through the ribs of the carapace, and thus insinuates itself 

 into the branchial cavity. It is not difficult to separate it 

 from the crab, to which we find it to be attached by cellular 

 tissue ; the anterior part of this ovarian body, that which is 

 placed in the viscera, becomes mature first, and consequently 

 it is much more dilated, a, while the other, b, which is situ- 

 ated between the ribs, is still immature, and retains the im- 

 pression of these solid parts. The ovarian sac is formed of a 

 transparent tissue, and contains in this state the graduated 

 series of the development of the ova which it encloses : the 

 most mature are in «, and are visible to the naked eye only 

 as a granular substance ; in the figure, however, they have 

 been drawn a little larger, in order to avoid confusion ; the 

 less advanced ones are in b. Seen by the microscope, the 

 latter are of a rounded form, c ; those which are a little less 

 immature are figured at m ; those which most nearly approach 

 maturity are uniform and emarginate, as at n ; lastly, the 

 hatched embryos have the form represented in r, and run in 

 all directions in the drop of water placed under the lens of the 

 microscope. These insects have the body divided into a great 

 number of rings, the first of which bears two eyes ; the tail is 

 bifurcate ; and the last joint of the first four pairs of feet is 

 claviform. 



" This insect belongs to the race of the Oniscus squilltformis, 

 very well described by Pallas ; it presents a certain analogy 

 with the species described under the name of Oniscus locusta* 

 by that illustrious naturalist, a species very frequent in the 

 organic rubbish thrown up on the sand and bathed by the 

 sea in its movements to and fro ; it is our sand-flea. How- 

 ever, the species which is developed at the expense of the 

 blood of the crab is much smaller than this sand-flea. It is 

 true that I have been able to see this insect only at the 



scoglio fin che in mare precipiti, o vero in una prossima buca si rimpiatta : 

 percio dai nostri pescatori si cliiama Granchio spirito." 



In the same memoir Oavolini describes and figures : — 1, a Gregarina 

 parasitic on the Grapms, which he calls Taenia ; 2, the zoea of the <!rit;>sf^ 

 (pi. ii. figs. 7,8, & 9). As early as 1708 Slabber, for his part, bad discovered 

 the metamorphoses of the Decapods ; but it was only in L823 that Vaughan 

 Thompson generalized these observations, which had boon completely 

 forgotten. 



* 'Spicilegia Zoologica,' fasc. ix. pp. 50-55 (Barolini, 1/G7). 



