350 EEA'. T. E. E. STEBBIXG OK KEW SPECIES OF AMPHIPODOUS 



long slender flagellum, when that, not being in use, is laid for security beneath the 

 animal's body. For the two species which Dana named CJydonia rjracilis and Clydonia 

 longipes, Bovallius accepts from Dana a division between the fifth and six segments 

 of the pleon. Streets, in describing what he regarded as a specimen of Clydonia 

 lonqipes, says that the fifth and sixth segments in question are apparently consolidated. 

 Since in all the species which have been recently examined these two segments are 

 coalesced, it is most probable that their separation was not observed by Dana, but 

 taken for granted, contrary to the actual fact, although according to what is normal in 

 the Gammaridea, to which he assigned the genus Clydonia. 



Genus Scina, Prestandrea, 1833. 



1833. Scina, Prestandrea, Effemeridi scientifiche e letterarie per la Sicilia, t. vi. p. 10. 

 1840. Tyro, Milne-Edwards, Hist. Nat. des Crustaces, t. iii. p. 80. 

 1849. Clydonia, Dana, American Journal Sci. and Arts, vol. viii. no. 22, p. 140. 

 1885. Tyro, Bovallius, On some forgotten Genera among Amph. Crust, p. 12. 



1887. „ Bovalliu.s, Mouogr. Ampli. Hyperiidea, K. Svensk. Vet.-Akad. Handl. Bd. xxi. 



no. 5, p. 5. 



1888. Scina, Stebbing, Challenger Ampliipoda, pp. 151, 1271, &c. 



1889. Fortunata, Chun, Akad. der Wissenschaften zu Berlin, Math. u. naturwiss. Mitth. p. 342. 



1889. Scina, Chun, Zoologisoher Anzeiger, Jahrg. xii. no. 308, p. 286. 



1890. „ G. O. Sars, Crustacea of Norway, vol. i. pt. 1, p. 18. 



The other references will be found in the Monograph of the Hyperidea by Bovallius 

 and in the Report on the ' Challenger' Amphipoda. The genus at present stands by 

 itself, and may therefore be content with the character of the family. Nevertheless, 

 Bovallius and Sars have drawn out separate generic descriptions. Bovallius in his 

 definition speaks of the third perseopods as "transformed into jumping-legs." For 

 such a function they do not seem particularly well suited. The long and strong second 

 pint is directed forward and upward, and is prolonged into a spine-like process at 

 the apex of the front margin. According to Professor Chun, by aid of these processes, 

 the animal attaches itself to a free-swimming hydrozoon, and floats about without 

 exertion after the fashion of Phronima and various other Hyperidea. Sars states that 

 the third perseopods are the longest, which is indeed usually a conspicuous feature ; but 

 the Scina hovallii of Chun is said to have the fourth persopods somewhat longer than 

 the third, and Scina clausi (Bovallius) to have the fourth as long as or a little longer 

 than the third. Of the uropods Sars declares the first and second pairs to be " simple, 

 with the peduncle not defined." Yet both in his own species, Scina horealis, and in 

 all the other known species, with one or two doubtful exceptions, the extent of the 

 peduncle is defined in all the uropods by the presence of a free outer branch, albeit 

 that branch is sometimes extremely small and spine-like. There are more or less 

 conspicuous gland-cells in the limbs of the perseon and the uropods. The pleopods 



