T. XJIl] CRUSTACEA CASPIA. 463 



two sexes; 3rd and 4th pairs in female with a small Particulate appendage 

 (rudiment of exopodite) on the basal joint. Pleopoda in male 2 pairs, both 

 imperfecta* developed; the anterior ones consisting each of a laminar basal 

 part edged inside with strong plumose setse, and a single small ramus carrying 

 at the tip a few curved setse; the posterior ones quite rudimentär}', forming 

 2 small claviform appendages, without any setse, but each carrying outside 

 a strong spine. Uropoda with the inner ramus uniarticulate, the outer 

 Particulate. Telson very small, unarmed, but distinctly defined from the 

 last segment. 



Remarks. — The present genus, the type of the family Pseudocumidœ, 

 was established by the author in the year 1864, to include a Norwegian 

 species, which he at first described as Pseudocuma bistriata, but subsequently 

 identified with a form rather imperfectly described by Prof. P. v. Beneden 

 as Leitcon cercaria. In 1876 the same species was also found to occur in the 

 Mediterranean, and, in addition, another nearly-allied species, P. ciliata, was 

 detected. Though the author has had an opportunity of examining numerous 

 Cumacea from very different parts of the Oceans, no other species of this 

 genus had before come under his inspection. It was therefore highly per- 

 plexing to find this genus, so poorly represented in the Oceans, truly abounding 

 in species in the Caspian Sea, and, moreover, presenting forms of a very 

 considerable size, as compared with the 2 earlier known species. As above 

 stated, the Caspian species also exhibit a most wonderful diversity as to their 

 outward appearance, some to certain extent recalling in form the genus Dia- 

 stylis, others the slender genus Iphinoë, while others again exhibit a perplex- 

 ing resemblance to the genus Eudorella. The question now arises, whether 

 all these forms can in fact be assumed to have immigrated in some remote time 

 from the Oceans, or whether they may, under particularly favourable con- 

 ditions, have developed themselves independently from a few, or even a single 

 primitive form. The scantiness of species of this genus in the Oceans would 

 indeed seem to support the latter supposition. In every case the character 

 of the Cumacean fauna of the Caspian Sea, as yet known, is so highly remark- 

 able, that some hypothesis is needed to explain it satisfactorily. 



With the exception of P. pectinata, which has recently been detected by 

 Mr. So win sky in the Sea of Azow, all the species here described are, as yet 

 known, wholly restricted to the Caspian Sea. 



1. Pseudocuma pectinaia, So whisky. 

 (Pi. I & II). 



Pseudocuma pectinaia, So win sky: paKoo6pa3HMXi> A30BCKaro Mopa, coopaHHbixt 

 A. A. OcTpoysiOBtiMt bo Bpeim njiaBaHÏH Ha TpaHcnopT-s «KasöeicB» .tbtomt. 1891 ro^a. p. 7. 

 (ITpoTOKO.ifci KieB. 06m,. EcTecTBOncntiTaTejieK 1892). 



Bulletin H. S. IY (XXXVI) p. 290. 33* 



