139 



OVISACS. Of about equal size, elongated oval (fig. 2 b); the specimen represented 

 measures 71 mm. in length and -46 mm. in breadth. Eggs numerous, about middle-sized. 

 Judging from the size of the ovisacs, the adult females of this species must be supposed to 

 be 1 mm., or somewhat more, in length. 



LARVA. A specimen found free (fig. 2f) is -16 mm. long. Cephalothorax more than 

 Vs time longer than broad. The front with a long, almost straight list inside the base of 

 the antennula. Antennulae 3-jointed; olfactory seta about three times longer than the an- 

 tennula and scarcely half the length of the cephalothorax. Antennae much as in the larva 

 of S. intermedia. Of the maxillulae only a single seta has been discovered. First joint of 

 the maxillae of a little more than medium length, smooth; the two others normal. Second 

 joint of the maxillipeds shorter than the third. Abdomen small, its first segment somewhat 

 longer and a trifle broader than the second, and its long seta reaching a little beyond the 

 ends of the caudal stylets; second segment scarcely longer and not broader than the third, 

 from which the relatively good-sized caudal stylets are well set off, but their long setae are 

 defective in my two larvae. 



POST-LARVAL DEVELOPMENT. A single pupa (fig. 2g) found on the glass 

 during the preparation is -17 mm. long and '11mm. broad; it is described above on p. 60. 



HABITAT. Ampelisca tenuicornis Lilljbg. from Denmark. I have found the 

 parasite on nine specimens, six of which were rather young, without marsupium. On each 

 of five of these occurred a not half-grown or very small female (in one case it was evidently 

 just hatched); on the sixth specimen I found two free larvae. In a specimen with half- 

 developed marsupium occurred one not half-grown female. The two other hosts were females 

 with fully developed marsupium ; in one of them occurred five ovisacs, in the other the above- 

 mentioned flattened female and four of the host's own eggs. 



REMARKS. By the very long setae of the trunk-legs this species is easily di- 

 stinguished from all other hitherto known species of this genus. 



22. Sphaeronella Amphilochi n. sp. 



(PL VII, flg.3a-3b). 



FEMALE. The only specimen found was adult and measured -54 mm. in length 

 and -40 mm. in breadth. The head (fig. 3 a) is well defined from the trunk. The frontal 

 margin with short and very fine hairs. Antennulae tolerably long, with pretty long setae. 

 Antennae 3-jointed, the basal joint appears shorter than the following joints; the terminal 

 seta about the length of the last joint. Mouth-border of about medium breadth. Maxillulae 

 with rather short additional branch. Basal joint of the maxillae smooth. Basal joint of the 

 maxillipeds long, slender and naked, second and third joints coalescent, last joint ending in 

 a point. Sub-median skeleton naked, but a peculiar characteristic in this species is that the 



18* 



