EPizoA. 269 



tremities exist only in the form of a few minute pairs of obtuse inar- 

 ticulate processes (b). In the higher organised species, the adhesion 

 is effected by suctorial (/tg- 116, ?n) or prehensile limbs, or by jointed 

 mandibles, with terminal hooks or forceps (Jig. 1 1 5, b). The head, 

 in most of the species, is found, when closely examined, to present a 

 pair of jointed antennae (Jigs. 115, f, 117, c), which, contemplated by 

 the experienced naturalist, cognisant of the value of such characters, 

 might excite the suspicion that relations to higher Articulata than 

 the Anellids were hidden under the bloated form which indolent 

 and gluttonous habits had superinduced upon the pendent parasite. 

 Observation of it during its early and locomotive state has proved 

 this to be actually the case to an extent which could not have been 

 anticipated. 



The Epizoa are of distinct sexes: the male (Jig. 117) appears 

 always to retain his freedom, and is, perhaps on that account, singu- 

 larly smaller than the female, generally not more than a fifth part of 

 her size ; consequently, for a long time, the males escaped recognition. 

 They adhere to the vulva of the other sex with one antenna usually 

 inserted therein. The female individuals, distinguished throughout 

 a great part of the year by their pendant ovisacs, are the examples 

 usually seen of this curious class ; and in these I shall proceed to 

 describe the anatomical characters of the Epizoa. 



The body, independently of the ovisacs, is generally divided into 

 two segments : the anterior and smaller division sometimes supports 

 a distinct head, but more commonly corresponds with the cephalo- 

 thorax of the Crustacea: the larger segment is called the abdomen, 

 and in it the ovaria are developed. You will not unfrequently find 

 adhering to the eye of the sprat an Epizoon or Lernsea *, which is a 

 nearly allied species of the same genus (Peniculus) as the specimen 

 figured and described by Nordmann (Jig. 112)t, which infests the 

 boar-fish (Zeus aper). In the Peniculus Jistula, the head (Jig' 114, 

 A), is oval and notched anteriorly, each division being armed with an 

 inwardly bent hook, or rudimental jaw (c). The mouth (a) is imme- 

 diately beneath these, in the form of a circular orifice, supported by a 

 short cartilaginous tube. At the posterior contracted part of the 

 head are two pairs of short, oval, flattened processes (b) : a constric- 

 tion or neck separates' them from the thorax, at the commencement 

 of which there is a third pair of similar rudiments of locomotive 

 appendages. The thorax (t) is round, and separated by a constriction 

 from the abdomen (a b), a fourth pair of appendages (b) being de- 

 veloped from the interspace. The basis of the smooth parchment- 

 like integument is chitine. The alimentary canal (d) is much 



* CCVIII. t LXXI. Heft. ii. 



