HERMIONE HYSTRIX. 269 



are not yet present. Besides the structures mentioned, the young Hermione has now 

 three pairs of eyes, and a process (first foot) behind the collar. 



Savigny (1820) first distinguished the species, though his description is by no 

 means diagnostic. 



Delle Ohiaje (1823) refers to the condition of the alimentary system in speaking 

 of the anatomy of Pleurophyllidia, and gives a figure of a moribund example in his 

 ' Memorie.' He thought the papillae of the proboscis were taste-organs. He shows the 

 globules of the blood. In his ' Descrizione ' he mentions its common occurrence at 

 Naples, and reproduces the plate from the ' Memorie.' 



The Aphrodita hystrix mentioned by Oersted 1 probably refers to Lsetmatonice. 



Kinberg (1858) followed De Quatrefages in making two species, viz. H. hystrix and 

 H. hystricella ; but so far as can be ascertained this distinction rests upon variation, and 

 Claparede was of the same opinion. 



De Quatrefages (Anneles) saw in a male Hermione hystrix the spermatozoa issue in 

 the form of a white thread at the base of the inferior branch of the foot of the nineteenth 

 segment. They probably escaped from the segmental papilla between the feet. This 

 author distinguishes between his H. fallax and this species by the fact that the median 

 antenna in H. hystrix is least, and that the bristles of the scale-bearing feet have the 

 points unarmed, while those of the inferior feet are tridentate (instead of the tips 

 straight and the inferior bristles bidentate as in H. fallax). The bristles of the ventral 

 division have curved apices, whereas in H. hystricella from the Mediterranean, &c, these 

 are straight, and Kinberg says so also. 



Claparede 2 has already pointed out that De Quatrefages was wrong in thinking that 

 absolute reliance was to be placed on the number of the denticles at the tip of the spines 

 or of the ventral bristles, and he also showed the condition generally of the anterior feet 

 in contrast with the posterior. He enters into the uses of the guard for the tips of the 

 long dorsal spines, and demonstrates that a process also appears in the developing ven- 

 tral bristles before they pierce the surface. He alludes to the granular bristles, which 

 had previously been described by Johnston and Kinberg, and points out the nature of 

 their tips, with the swollen part beneath the point, as shown in one of the present figures. 

 He mentions having found in a single example a long, simple bristle in the ventral division 

 of the foot, probably a pathological phenomenon. He speaks of the warts on the 

 surface, already mentioned by Pallas, Johnston, and Kolliker. He likewise alludes to 

 the structure of the peritoneum, and that of the dorsal cirri. 



Grube (1874) says De Quatrefages relegated Hermione hystrix to the Mediterranean 

 and H. fallax to the Atlantic. 



Prof. Jourdain, 3 in his account of the histology of the integument and sensitive 

 appendages of this species, describes the irregular polygons formed by the cells of the 

 epithelial coat, the nerves which ramify in it, and the thinly distributed nerve-cells. On 

 the ventral surface, the warts, of which Claparede had formerly given a figure, have a 

 central pore, through which communication with the granular layer of the epidermis 



1 ' Annulat. Danic. Consp./ p. 11, 1843. 



2 < Ann. d. Golfe d. Nap./ p. 50, 1868. 



3 'Archives Zool. Experiment/ (2), vol. v, p. 91 (1887), pis. hi and iv. 



