189 



Mysidion, occurred two parasites, one of whieli — a female with twelve ovisacs — was 

 placed to the front on the carapace, a little to the left of the median process, the other — 

 a female with tlu-ee ovisacs — was placed on the dorsal side of the last thoracic segment. 

 On a young individual without marsupium appeared two parasites, one of them — a female 

 without eggs — neai-Iy in the centre of the back of the second abdominal segment, the 

 other, a female with two males hinged by their frontal threads (fig. 3c), somewhat to the 

 right side on the back of the first abdominal segment. In a hardly adult female (from Kvalo), 

 on the dorsal part of the second abdominal segment (fig. 3 b), I found an adult female with 

 two minute ovisacs without eggs, and four larvae (v), one of which fell ofi' on being touched, 

 so that it was not drawn in fig. 3b, but it is the specimen represented in fig. 3 m with an 

 adult male beneath the larval skin. 



5. Er. abyssorum Gr. 0. S. On a female with empty marsupium : five parasites, viz. 

 two very small females on the right side of the thorax close behind the carapace; and at a 

 short distance in front of these animals, on the carapace itself, one small and one good-sized 

 female, to the latter of which was attached near its mouth a strongly impaired male with 

 a large spermatophore , and the anterior half of another male was fixed by a thread to the 

 side of the trunk; finally: at the centre of the dorsal surface of the sixth abdominal segment, 

 a good-sized female (fig. 3f and fig. 3g) — all parasites without ovisacs. In a female (from 

 Kvalo) with Mysidion ahyssorum in its marsupium, occuired five parasitic females, all on 

 the carapace; one of them, wliich was very small, was situated somewhat behind the middle 

 of and a little above the left lateral margin, the four others were placed close together at 

 some distance behind the centre on the back and a little down on the right side; one of 

 these was very small, the two others a little larger, the fourth large, without ovisacs, but 

 with two larvas attached to it. On an adult male (fig. 3a) appeared altogether nine parasitic 

 females and one larva: one female (a) with six ovisacs is placed on the left hand side of 

 the carapace ; somewhat behind it and further up towards the back, the larva (1) is situated ; 

 in an irregular transverse row on the dorsal side of the first abdominal segment are found 

 altogether five females, one of them pretty small, the four others large (a), two of them each 

 with one, the two others together with many ovisacs, wliich can scarcely be counted accu- 

 rately without a dissection; on the back of the second abdominal segment is placed a female 

 with seven ovisacs, as well as a male (m) hinged to the female by a long tlu-ead, which 

 had tlie larval skin on its anterior end; to the right of the latter large female is found a 

 very small female, and on the boundary between the second and the third abdominal 

 segment, a tolerably small female (in the illustrati<in the last two specimens are marked b.) 



REMARKS. I must consider the parasites on all five species as belonging to the 

 same species. In the females of the four smaller species of hosts, the distance between 

 the genital apertures is fi'om much to a little smaller than the diameter of each ring, in 

 not full-grown individuals of the largest specimen, Er. ahyssorum, this distance varies from 

 being a little shorter than to about the same length as the diameter, but in the adult spe- 



