170 



IV. Clioiiiostoma h. j. h. (isse). - - 



FEMALE. The body is somewhat flattened; seen from below, it is broader than 

 long, nearl}^ pentagonal, with rounded angles, one of wliich forms the centre of the posterior 

 margin, and two on each side, whereas the anterior margin forms but a slight curve and 

 is longer than the distance between the lateral angles on each side, and between the 

 hindmost lateral angle and the posterior central angle. The head is situated on the 

 ventral side a little behind its anterior margin, and the skeleton is transformed into a 

 transverse ring-shaped frame which is considerably broader than long, and the anterior part 

 of the frame, wliich forms the frontal border, may sometimes rise a little above the skin in 

 front of it, whereas the remainder, or sometimes the whole frame, is on a level with the 

 ventral plane. The frame surrounds a good-sized, thin-skinned area, in or a little beliind the 

 middle of which the rostrum and the mouth-appendages are found. The antennulae ai'e nor- 

 mal, 3-jointed and inserted on the ring. The antenna are certainly 3-jointed and furnished 

 with a terminal seta. The mouth is good-sized, the mouth-border of about average breadth. 

 Maxillulse well developed, with a long additional branch. Maxillae powerful, constructed as 

 in the typical species of Sphceronella. Maxillipeds rudimentary ^ each consisting of two very 

 small or quite diminutive joints. Trunk-legs and caudal stylets — where such are found — 

 as in Sphceronella. The genital area is more than twice as broad as it is long; the tliickest 

 cliitine is found in the middle and along the lateral margins; the genital apertures are 

 situated close together in the middle of the area, and close in front of them appear the 

 orifices of the long sausage-shaped receptacula semiuis, which are turned obliquely forward 

 and outward. — No spermatophores have been observed. 



MALE. Unknown. 



OVISACS. They are always deposed freely, their shape is sub-globular, and as 

 many as eleven or twelve may be found in one female. Each ovisac contains an exceedingly 

 great number, on an average at least one thousand, minute eggs (comp. my figures p. 47). 



LARVA. Is known of both species and is quite similar in structure to the larvae 

 of some of the species of Splmrunella living in Amphipoda; the only differences are, that 

 the cephalothorax is shorter and broader, and the spiniform setae at the posterior angles 

 of the first abdominal segment longer, and especially tliicker, than in any Sphceronella 

 known to me. 



POST-LARVAL DEVELOPMENT. The pupae found are described in detail above 

 on p. 56 — 57. 



HABITAT. The branchial cavity of two species of the genus Hippolyte Leach 

 belonging to the order Decapoda, and the presence of the parasite causes the part of the 

 carapace which is situated above the intruder and its ovisacs to vault strongly, so as to 

 form a large swelling, wliich as a rule is exactly similar to that caused by Qyge Hippolytes 



