26 REV. T. E. R. STEBBING— BISCATAN PLANKTOX : 



*S'. marginata is distinguislied from all other definitely known species of the genus except 

 Scina incerta, Chevreux, and from the latter, in Chevreux's words, " sous tons les autres 

 rapports, elle differe absolument." Thus in the third perseopods there are teeth along 

 the front margin which are wanting in ^S*. incerta ; the sixth joint is much shorter than 

 the fourth instead of being equal to it in length ; the whole limb is considerably instead 

 of only a little longer than that of the fourth perajopod ; and the fifth pair are more than 

 half the length of the fourth, while in S. incerta they are only a third of the length of 

 the preceding pair. 



Length of single specimen 4j"5 mm., the first antennae representing 1-25 mm. of this 

 measurement. 



Occurrence: 35^. 260 to 150 fathoms. 1 specimen. 



9. Scina Rattrati, Stebbing. 



1895. Scina rattrayi, Stebbing, Trans Zool. Soc. London, vol. xiii. pt. 10, p. 358, pi, 53 a. 



1900. Scina Rattrayi, Chevreux, Ampliipodes de PHirondelle, p. 123, pi. 15. fig. 2. 



1901. Scina Bovallii, Vosseler (not Cliun), Amphipoden der Plankton-Exp. p. 105, pi. 9. figs. 8-17. 

 1901. Scina Rattrayi, Lo Bianco, Mittheil. Stat. Neapel, vol. xv. pp. 422, 446. 



1903. Scina Rattrayi, A. 0. Walker, Ann. & Mag. Nat. Hist. ser. 7, vol. xii. pp. 223, 231. 



This species was originally described from a single female specimen. Chevreux had 

 at his disposal two male adult specimens, one young male and one female. He 

 describes the second antennse as observed in the adult males. Vosseler describes an 

 adult male and a young female under the designation " Scina Bovallii, Chun." In 1889 

 Chun applied the name Fortunata lepisma to two specimens, which later in the same 

 year he divorced under the separate names of Scina lepisma $ and Scina Bovallii 6 . 

 But if the ruling be accepted that the female which Chun described and figured belongs 

 to the earlier >S'(?^/m marginata (Bovallius). it follows that the name Scina lepisma will 

 cling to the male form. 



There cannot be any reasonable doubt that Vosseler's Scina Bovallii is identical with 

 my Scina Rattrayi, which had, unluckily, not come under Dr. Vosseler's notice when he 

 published his valuable treatise on the Hyperiidea of the Plankton Expedition. He 

 recognizes, however, that the identification which he actually adopts without hesitation 

 presupposes several defects in Chun's figure and description of the species. In regard 

 to tlie tliird perseopods, Chun states that the fourth joint is shorter than the fifth, also 

 that it is shorter than the sixth, and that the finger is long. But in this limb of Scina 

 Mattrayi the finger is minute, and the fourth joint is much longer than all the 

 following joints combined. Chun says that the fourth perseopods are somewhat longer 

 than the third, and Vosseler says the same of the species which he describes ; but his 

 figures of these limbs do not support this statement, nor does it apj^ly to Chevreux's 

 figures of Scina Battrayi, nor to the specimens which I have examined. Chun 

 institutes a comparison between his species and Scina horealis (Sars) and Scina Clausi 

 (Bovallius), pointing out that the differences rest chiefly on the form of the third and 

 foui'th perseopods, and oq the circumstance that the last-mentioned couple of species 

 have each five pairs of branchial vesicles, whereas in his own sjiecies there are only four 



