138 M. A. Giard on the Genus Entoniscus. 



marks*. In order to elucidate some doubtful points in the 

 degraded organization of the Cryptonisci, I was obliged to 

 have recourse to the examination of other Bopyridte of less 

 anomalous structure. I have thus collected materials of con- 

 siderable importance upon this family of Isopods. But most 

 of these animals are of great rarity ; and the difficulty of 

 tracing their embryogeny is also very great — a single female 

 containing a great number of ova, it is true, but all in the 

 same stage of development. Hence I have not yet been able 

 to bring the monograph which 1 have projected to a point of 

 perfection sufficient for the commencement of publication. I 

 will now, however, at least make known some results obtained 

 in the case of a very sparingly distributed genus, the genus 

 Entoniscus'f. I hope by this means to hinder from useless 

 researches those who might be tempted to attack the same sub- 

 ject, and to furnish some data which will be made use of 

 hereafter for a more general treatise %. 



The genus Entoniscus, established by Fritz Miiller in 

 1862, includes animals which had been met with by Cavolini 

 as long ago as 1787. Cavolini had observed Sacculince upon 

 several species of crabs ; and he regarded these parasites as the 

 broods {ponte) of a small species of Cyclops grafted by the 

 mother upon the tail of the Brachyurans. After bringing 

 forward his observations upon this subject he adds : — 



" Besides the Cyclops which we have just described, there 

 is in the sea another insect which fixes its brood upon the 

 body of our crabs, but in a manner much more inconvenient 

 for those animals. It is, in fact, in the very midst of their 

 viscera that the eggs are attached. Hitherto the Depressus § 



* Giard, "Sur l'ethologie de Sacculina carcini," Conrptes Rendus de 

 l'Acad. des Sciences, 1874. 



t A preliminary communication upon these animals has been printed 

 in the Comptes Rend usde l'Acad. des Sciences (12th August, 1878) . See 

 Ann. & Mag. Nat. Hist. ser. 5, vol. ii. p. 340. 



% I have already indicated briefly certain conclusions of this memoir. 

 See Arch, de Zool. exper. torn. ii. 1873, p. 513, and torn. iii. 1874, Notes et 

 Revue, pp. iii & iv. 



§ It is impossible not to recognize Grapsus varius in the fine descrip- 

 tion given by Cavolini of his Granchio depresso :— 



" Questo granchio e copiosissimo per gli scogli del nostro cratere, e 

 sembra godere piuttosto di stare in secco, massimassime quando, pel 

 calor della state, le acque presso i lidi si riscaldano, o si albanano : su di 

 questi scogli di erbe vestiti e curiosa cosa vedere come in terra seduto, 

 or con una, or con ambe le mani, colga quella verde conferva e alia bocca 

 l'accosti. La forma del suo corpo e quadrilatera schiacciata, il colore di 

 un verde cupo : le bracda son crasse e valide poco meno del paguro 

 (JEriphia spinifrons of modern authors) ; la sua carne e mucilagginosa, 

 e molto poca. Ma cio che lo rende singolare, e la velocita, del eorso : 

 bisogua esser destro per dargli sopra la mano ; altrimenti o f ugge sullo 



