the British PandaKdae. 33 



its outer side. The external edge is distinctly concave, the 

 whole scale curving slightly outwards from the base. 



The third maxittipeds agree closely with those of P. Mon- 

 tagui. 



The second perceopod on the right side (PI. III. fig. 2,f) 

 is shorter and stouter than the corresponding appendage of 

 P. Montagui, only reaching to or falling a little short of the 

 tip of the antennal scale. The carpus is divided by four 

 articulations into five segments, of which the first occupies 

 about one half the length of the carpus, while the next three 

 are subequal and together equal the length of the fifth seg- 

 ment. The chela is much stronger than in P. Montagui. On 

 the left side the second leg is shorter than is usual in P. Mon- 

 tagui, just reaching to the tip of the rostrum. 



The remaining thoracic legs, on the other hand, are longer 

 and more slender than in P. Montagui, those of the third 

 pair reaching considerably, and those of the last pair a little, 

 beyond the tip of the antennal scale. The dactyl is a little 

 longer and more slender than in the type species (PI. IV. 



fi g- 2,#). 



In the first pleopods of the male the endopod (PI. IV. 

 fig. 2, h) differs from that of P. Montagui in having the pointed 

 inner process very short, while the rounded outer lobe is more 

 prominent than in that species, so that both reach about the 

 same level. In the second pleopods of the male the appendix 

 masculina slightly exceeds the appendix interna in length. 



The telson bears on its upper surface five pairs of spinules 

 in all the specimens examined. 



The three British specimens of this form which I have seen 

 agree in all essential points with Sars' original description 

 and with a very fine female specimen from Norway presented 

 to the Museum of University College by Prof. Sars. Two 

 specimens from the American coast presented by the Smith- 

 sonian Institution differ in the larger number of teeth on the 

 rostrum, j in the one case and l j in the other; both, how- 

 ever, have, as usual, three spines on the carapace. The 

 American specimen figured by A. Milne-Edwards (I. c.) has 

 ^ rostral teeth, and of these four are on the carapace, as is 

 usual in P. Montagui. Smith (I. c. 1881) records an ab- 

 normal specimen in which the usual characters and proportions 

 of the right and left chelipeds were reversed *. 



* Smith also found an example of the same abnormality in P. lepto- 

 cerus. Boas (' Decapodernes Slsegtskabsforhold/ 1880, p. 35 (57)) states 

 that in P. borealis the longer chela is sometimes the right, sometimes tbe 

 left. 



Ann. & Mag. N. Hist. Ser. 7. Vol. iii. 3 



