108 • Miscellaneous, 



On. the Morpholof/y and Si/stem die Position of the Epicarides of the 

 Family Dajidae. By MM. A. Giard and Jules Bonnier. 



In a previous paper (see ' Annals,' ser. 6, vol. iii. p. 512), for reasons 

 derived from the ethology of the animals, we have regarded the 

 Dajidae as a group intermediate between the Cryptoniscians and the 

 Bopyrians proper, with which they would be connected by the 

 family of the Phryxians. This view is now confirmed by the anato- 

 mical investigations which we have been enabled to make of some 

 types of this group, which is still so little known and so badly 

 represented in collections. 



The Rev. A. M. 2^orman has been kind enough to send us a speci- 

 men of Da/us mysidis, Kroy., collected at the island of Jan Mayan 

 upon a Mysis ocidata, Fabr., during the Austro-Hungarian expedition 

 to the arctic seas *. He has also submitted to our examination an 

 Aspidophryxus parasitic upon Erythrops microphtJialma, G. 0. Sars, 

 and dredged by G. 0. Sars himself upon the Norwegian coast. 



The unique specimen of Dajus mysidis figured but not described 

 by Kroyer was a young female, accompanied by a male in the 

 Cryptoniscian stage. The six females collected at Spitzbergen 

 during the Dutch ' Willem Barents ' expedition and studied by 

 Hoek were also immature, and only one of them bore a male in the 

 second larval form, Buchholz alone has described the adult male 

 and female of Dajus mysidis, Kriiy., iinder the name of Lepto- 

 phry.vus mysidis f. But his description is very incomplete, espe- 

 cially with respect to the inner antennae and the incubatory plates. 



Of the latter there are five pairs as in all Bopyrians, and the fifth 

 pair, which escaped the notice of Gerstacker, is the most developed. 

 This forms the greater part of the incubatory cavity. The body, 

 bent ventrally on each side, also takes part in the formation of this 

 cavity. The morphology of the head and thorax diff'ers little from 

 that of the same parts in the Phryxians. However, the feet of the 

 sixth and seventh thoracic segments are entirely wanting, thus 

 reproducing an embryonic arrangement which is transitory in the 

 other Bopyrians. Further, the first five pairs of feet are very 

 closely approximated to the anterior part of the animal, where they 

 surround the aperture of the incubatory chamber. The metameri- 

 zation is very visible upon the middle of the dorsal part in both the 

 abdominal and the thoracic regions ; in the latter the segments 

 increase in size from before backward. On the pleon the first pair 

 of feet alone are well developed in the form of biramose lamellae, 

 which, in this part, close the incubator)- chamber. The other 

 pleopoda are rudimentary, with no pleural laminae ; there are two 

 uropoda. 



• We keep the name of Dajus mysidis, Kroy., for the parasite of Mysia 

 oeulata, and give that of Dajus mixtus to the Dajus found by G. O. Sars 

 at "Vadsoe upon Mysis mixta, Lillj. 



t ' Zweite deutsche Nordpolarfahrt in den Jahren 1869 und 1870,' 

 Bd. ii. Ahth. i. p. 287, Taf. ii. fig. 2 (Leipzig, 1874). 



