95 



(fig. Ill) and very slidit liairs. Basal Joint of the maxillipecls rather slender and a good 

 deal longer than half of the breadth of the head at its base. The genital area (fig. 3a) 

 moie than double as broad as long; between, behind and obliquely outside the genital apertures, 

 as well as beliind the caudal stylets, are a number of very fine hairs. 



MALE. A normal specimen (fig. 1 i and fig. 1 k) is "20 mm. in length and W nnn. 

 in breadth, or about half the length of a middle-sized adult female (comp. fig. 1 d with fig. 1 b 

 and fig. Ic). The body between scarcely double and a little more than double as long as 

 broad. The frontal maigin seems to be like tliat of the female; the incisions are extremely 

 difficult to see (the hair-covering in fig. 11 is too long). Basal joint of the maxillipeds of a 

 shape similar to that of the female. Trunk-legs and caudal stylets long, longer than half 

 the breadth of the body, and very distinctly fiii-nished with haiis about all over the distal half. 



OVISACS. Of medium or rather large size, globular or shortly ovate (fig. le and 

 fig. If). As a rule there are fourteen to eighteen very large eggs in each sac. It is a not 

 common occurrence to find eight ovisacs with one female, and a greater numbei- has never 

 been observed. 



LARVA. A free specimen (fig. Ig) is 15 mm. in length. Its cephalothorax is 

 neai'ly double as long as broad. Having only one such specimen in hand, I prepared some 

 larvae out of their egg-membranes and examined them more closely; one of them is seen in 

 fig. 11. We notice that its cephalothorax is still somewhat shorter and broader than that 

 of the freely swimming larva, and the animal is only 14: mm. in length. The olfactory seta 

 of the antennulse turned backward reaches beyond the posterior extremity of the ceidialothorax. 

 Distance between the maxillae and the maxillipeds about as long as the basal joint of the 

 latter. Second abdominal segment as long as the first. The longest seta of the caudal 

 stylets considerably longer than half the length of the cephalothorax, about half the length 

 of the body in the free specimen. 



POST-LARVAL DEVELOPMENT. Described in detail above, on p. 55. 



HABITAT. In the branchial cavity of Diastylis hicifera (Kr.) from Denmark. The 

 parasite I have found in sixty-six specimens, the special locality of fifty-seven of these are 

 unknown to me; five specimens were taken at Hellebaek (foui' by Dr. Joh. Petersen, one by 

 the author), and foui- in the following four stations of the expeditions of »Hauch«: Stat. 25 

 (110 fathoms), Stat. 368 (13 fath.), Stat. 370 (15 fath.) and Stat. 383 (14 fath.)'). Either 

 the right or the left side is infested ; in no specimen have I found both sides infested. Only 

 one female and generally also one male, rather seldom two males, are found in the same 

 branchial cavity. Where the parasite has laid several ovisacs, the carapace of the host is very 

 considerably swollen, and frequently this swelling rises somewhat above the median dorsal line. 



') Details about the exact locahties of these stations, the description of the bottom etc. is found in: 

 ,G. G. Joh. Petersen: Del videnskabelige Udbytte af Kanonbaaden ,Hauch"s Togler i de danske Have indenfor 

 Skagen i Aarenc 1883—86", p. 1 — 3."?, 1893. In my denrriirtions of several of the following species, other 

 stations from these cruises will be quoted and may be looked for in the afore-mentioned work. 



