8 E-ev. T. E.. R. Stebbing on Arctic Crustacea. 



variability in the number of the teeth of the rostrum both 

 above and below. Professor Smith's conclusion that no 

 specific distinction is tenable between polai'is and horealis has 

 been generally accepted. The American professor is also 

 inclined to believe that Hi^ypolyte cultellatay Norman, 1867, is 

 another synonym, and Norman himself (Ann. & Mag. Nat. 

 Hist. ser. 6, vol. xiii. p. 270) accepts it as such. It may be 

 noticed that cultellatum is a word used by Kroyer in describing 

 the rostrum alike of polai't's and horealis. The variability in 

 the pterygostomian spines (to disappearance) and in the 

 number of dorsal aculei (from four to ten pairs) on the telson 

 is fully discussed by Professor Smith. Koelbel gives the 

 branchial formula as comprising a podobranchia on the second 

 raaxilliped, an epipod on each of the five appendages from 

 the first maxilliped to the second trunk-leg, and a pleuro- 

 branchia on each of the five successive trunk-legs. As this 

 species has seven subdivisions to the fifth joint of the second 

 trunk-legs, or, in brief, a seven-jointed wrist, it seems proper 

 to include it in the genus Sinroutocaris. Hansen mentions 

 77 millim. as the length of a very large male. 



A large specimen (about 3 inches long), with others not so 

 large, was obtained at 70° 08' N., 4^)° 10' E., in 20 fathoms. 

 A small specimen (about 1^ inch long), with eight pairs of 

 dorsal spines on the telson and eight apical spines, of which 

 the median six are subequal, was taken at 76° 29' N., 

 19° 08' E., in 140 fathoms. 



Spirontocaris spi'nus (Sowerby). 



1805. Cancer spinus, Sowerby, British Miscellany, p. 47, pi. xxiii. 



1814. Aljjfueus sjjinus, Leach, Edinb. Eucycl. vol. vii. p. 481. 



1815. Alpheits spinus, Leach, Trans. Linn. Soc. London, vol. xi. p. 347. 

 1817. Hippvlyte Sutverbcci, Leach, Malac. Podophth. Britanuise, 



pi. xxxix. 

 1837. Ilippolyte Soiuerbyi, Milne-Edwards, Hist. Nat. Crust, vol. ii. 



p. 380. 

 1842. Hippolyte Soiverhei, Kroyer, Hippolyte's uordiske Arter, p. 90, 



pi. ii. figs. 45-54. 

 1879. Hippolyte spinus, S. I Smith. Tr. Connect. Ac. vol. v. pt. 1, p. C8. 

 1882. Ilippolyte spitms, Hoek, Crust. Willem Barents, in Nied. Arch. 



fiir Zool., Suppl. vol. i. p. 15, pi. i. figs. 4-7. 

 1886. Hippolyte spinus, Krelbel, Crustaceen von Jan Mayen, p. 11. 

 1888. Spirontocaris spinus, Bate, Rep. Voy. ' Challenger,' vol. xxiv. 



p. 596, pis. cvi., cvii. 



The synonymy may with little doubt be amplified by the 

 names Hippolyte Liljehoryi^ Danielssen, 1861, and Hippolyte 

 securifronsj Norman, 1863. Stimpson in 1860 adopts the 



