DESCRIPTION OF SPECIES 



313 



b. 



Fig. 12. Serolis convexa, Cunningham, 

 a, cutting edges of mandible: x 40. b, 

 form of spines on propodus of second 

 thoracic appendage of ?: > 40. c, form of 



extremity ; the inner lobe is delicate, about two-thirds the length of the outer, with its 

 distal half bent outwards, and with its distal end only slightly expanded and bearing a 

 single short seta. ~~--J)-_ 0- 



The maxilla is figured by Beddard (1884 Z), pi. vi, 

 fig. 14), but the sutures which correspond with those 

 already described and figured in the introductory part 

 of this paper are not shown. The fixed lobe is not much 

 larger than the other two, each of which bears eight or 

 nine pectinate setae instead of the more usual number 

 of two. 



The form of the spines on the propodus of the second 

 thoracic appendage of the adult male is shown in 

 Fig.i2c; according to Beddard (18846, p. 40) only a 

 single row of short hairs is present on the distal portion 

 of the longer variety of spines : as he points out, a tuft 

 of long plumose hairs is present on the carpus of this 

 limb. In examining the material of this collection, I 

 have observed for the first time that in this species 

 there is a sexual difi^erence in the form of the modified 

 spines on the propodus of the second thoracic appen- 

 dage. In the female, and also in the immature male, spines on propodus of second thoracic 

 as in the male, two kinds of spines are present in an appendage of cj: x 40. 

 alternating row, and those of the shorter variety are very similar in both cases. But 

 in the immature male and in the female the longer variety (Fig. iz b) consists of a 

 spine expanding distally into two processes, one of which is a little longer and broader 

 than the other ; between these the central axis is continued as a third arm to about the 

 level of the shorter of the two processes, where it ends in a bifid extremity. A similar con- 

 dition also occurs in S.gaudichaudii, Aud. et Edw., and probably in S. laevis, Richardson. 



The distribution of plumose setae in Beddard's figure of the last thoracic appendage 

 of the male is incorrect ; he figures them on the posterior margins of the ischium, merus 

 and carpus, but actually they occur on the merus, carpus and propodus. Incidentally, 

 he refers to this appendage in the text as the "sixth" instead of the last or eighth. 



Distribution. The type locality for this species is the north coast of Tierra del Fuego ; 

 Beddard's material was collected at Port William, Falkland Islands. The material in this 

 collection comes from off East Falkland Island and the Argentine RepubHc. 



[Serolis plana, Dana. 



S. plana, Dana, 1853, pt. ii, p. 794; Beddard, 18846, p. 39. 



This species has not been recorded since it was described by Dana in 1853. Beddard 

 (18846, p. 39) points out that it appears to be identical with S. convexa, Cunningham, 

 except that the eyes are stated by Dana to be conical in shape, whereas in S. convexa, 

 as in all the species of the genus, they are reniform. 



