(XXXVI)] CRUSTACEA CASPIA. 299 



two sexes; Srd and 4th pairs iu female with a small biarticulate appendage 

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

 imperfectly developed; the anterior ones consisting each of a laminar basal 

 part edged inside witli strong plumose seta?, and a single small ramus carrying 

 at the tip a few curved setaj; the posterior ones quite rudimentary, forming 

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

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

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

 last segment. 



Bemarks. — The present genus, the type of the family PseiidocumidcB, 

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

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

 identified with a foiin ratiier imperfectly described by Prof. P. v. Beneden 

 as Leiicon cercaria. In 1S76 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 Iphinoe, wiiile others again exhibit a perplex- 

 ing resemblance to the genus Eudurella. Tlie (juestion now arises, whether 

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

 from tlie Oceans, or whether tliey 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 suppoit the latter supposition. In every case the character 

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

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



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

 Mr. Sowinsky in the Sea of Azow, all the species here described are, as yet 

 known, wholly restricted to the Caspian Sea. 



1. Pseudocuma pectinata, Sowinsky. 



(I'l. I & II). 



P.«eu(?oci/Mia 7;ec<iHr(to, Sowiusky: |>aKooopa»iii.i.x'b -VaoiicKaro Mopn, cot'paiiiihixi. 

 .\. A. OcTpoysioiiMMi. 1)0 npt'Mii ii.iadaiiifi [la Tpaiiciiopxt <iKaaCeKi.» .li.TOin, 1891 roAa. p. 7. 

 (ripoToiio.iLi Kien. OOin. EcTfCTnoiicntiTaTeJcii 1892). 



Melanges biologiijncs. T. XMI, p. iC3. 



