EEPORT ON THE CEPHALOPODA. 115 



Off Dublin Bay (Ball); Isle of Wight (Forbes and Hanley); Firtla of Clyde (Scottish 

 Marine Station) ; Kattegat (Copenhagen Museum) ; " ad oras Bohusiae " (Loven). 



"Rossia Owenii Ball ? Ann. nat. hist. IX, 349 ; pinnis pone medium sitis, 

 brachiis basi discretis, acetabulorum insequalium serie tri-quadruplici armatis, tentaculis 

 validis, membrana apicali ad basin tori incipiente. — Abdomen ventricosum, satis ob- 

 tusum, latit. ad longit. = 28:38. Pinnae ad basin longitudine abdominis dimidium 

 prope sequantes, late ellipticse, antice per breve spatium limbi liberae. Caput magnum. 

 Brachia valida, 1, 4, 2, 3, ad basin brevissime colligata, exceptis Stiis, quae ad ^ longit. 

 4tis adnexa, his invicem profunde discretis. Acetabula, quorum in brachii singuli serie 

 laterali circ. 30, inde ab ima basi numeranda, inferius per paria disposita subalterna, 

 deinde per series obliquas tri- et quadruplices, brevissime pedunculata (nee louge, 

 cfr. 1. c), in brach l:is subaequalia, mediocria, in 4:is, 2:is, et praesertim 3:iis inaequalia, 

 lateralibus media duplo superantibus. Brachia 1 latere externo plica cutis marginali. 

 Tentacula valida, compressa, corpus longitudine aequantia, apice dilatata, revoluta, et intus 

 toro praedita lanceolato, membrana utrinque defenso, ex acetabulis confertis, versus apicem 

 sensim diminutis, superioribus baseos longe maximis, basalia brachii 1 :mi vix credentibus ; 

 membrana marginalis ad basin tori incipiens. Palpebra crassa, inferior oculum omnino 

 obtegens. Long. tot. = 85 mm.; ad basin brach. 1 = 58 mm.; latit. max. = 28 mm.; 

 long, gladii 23 mm. — Ad oras Bohusiae hieme semel capta." — (Loven, loc. cit.). 



There can be little doubt that as Steenstrup has suggested,^ the two forms described 

 by Ball are of different sexes and not of different species, although it is not true as 

 stated by Jeffreys ^ that he " considers R. Owenii of Ball the male, and his 

 R. Jacobii the female of R. macrosoma." The distinguishing characters indicated by 

 Ball are exactly those which mark out the sexes ; the males have enlarged suckers in 

 the two outer series on the lateral arms, while the females have smaller equal suckers, 

 and the body is more elongated, or, what is the same thing, the arms are " propor- 

 tionably shorter." The description of the membrane round the mouth given in 

 connection with Rossia jacobii is not of the nature of a specific character, being found 

 in many, if not most, genera of Decapoda. 



This species is very closely related to several others, many of the distinctive cha- 

 racters being only of a relative nature, as indeed is the case throughout the genus. It 

 differs from Rossia palpehrosa, Owen, in the greater equality of the arms and the 

 more posterior position of the fins ; it resembles Rossia hyatti, Verrill, very closely 

 in many respects (form of body, proportionate length of arms and umbrella, and number 

 of rows of suckers), but the fin is different in shape, wider, and less incised anteriorly, 

 and there are no papiUae on the dorsal surface. 



This species is certainly very closely allied to Rossia macrosoma, and should 



1 Heotocotyl., p. 199. ^ Bpit, Conch., vol. v. p. 134. 



