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I can indicate the special localities of only three specimens of B. pelagica: they were all 

 taken in the Kattegat on the cruises of the »Hauch«, two at St. 486 (in a depth from between 

 eight to eighteen feet, on sandy bottom, and the third at St. 113 (depth: four fathoms, on 

 coarse, white sand). — In order to give an idea of the unique degree in which this species 

 infests its host, it will be sufficient to copy my notes on the contents of the marsupium in 

 five of the most infested specimens. In one animal were found: three large females, all 

 attached, one to a gill, the other to one of the plates of the marsupium, further: two very 

 small attached females, seventeen males, three good-sized ovisacs and two larvae, one of 

 which was hinged to a gill. In another specimen were found: one large female, ten males 

 (at least three of which were lunged, one on each side of the same gill, the third to another 

 gill, and they were so solidly attached that I could examine the phenomenon more closely); 

 further: one ovisac, one rather broad larva and four thick larvae (»male pupae «). In a third 

 specimen were found : four females of very different size (in one specimen, the longest diameter 

 of which measured '41 mm., the ventral thread was '13 mm. in length), eight males, four 

 ovisacs, one narrower and one broader larva, as well as one »male pupa«. In a fourth 

 specimen occurred: one large and two small females, eight males, no ovisacs, four broad 

 larvae, sixteen »male pupae« (six of which were hinged on the gill of the third right leg 

 together with a broad larva) and one female pupa. 



In the marsupium of three specimens of Perioadodes longimanus (Sp. Bate) (= Mono- 

 culodes Grubei Boeck) from Denmark I have found females which I cannot possibly distinguish 

 from this species. In one specimen occurred: one female, the longest diameter of which is 

 •47 mm., and four ovisacs of sub-equal size, one of them was '39 mm. in length and - 30mm. 

 in breadth; on each of the other two specimens was found only one female, the larger one 

 of which measured '71 mm. On account of similarity in their mode of attachment, in the 

 structure of the antennulas with their long terminal setae, in the hairs on the frontal margin, 

 in the shape of the maxillae and of the maxillipeds and in the essential features of the 

 structure of the genital area, I must for the present admit these animals as belonging to 

 S.paradoxa, but as long as the male is not known, it is safer not to pronounce any definite 

 judgment about such small and rather difficult forms. 



REMABKS. The name of the species is chosen on account of the very peculiar, 

 hitherto unique, ventral attachment of the female. 



12. Sphaeronella abyssi n. sp. 



(PL IV, fig. 2 a— 2e). 

 FEMALE. The only specimen found was - 96mm. in length, ri3mm. in breadth, 

 somewhat irregularly crooked and rather flattened (fig. 2a). The head was squeezed against 



investigation. In this work I have accepted the established species in separating B. pelagica and B. Bobertsonii 



from each oilier according to the existence or non-existence of spines on the dorsal part of the fourth 



abdominal segment. 



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