324 



DISCOVERY REPORTS 



A. nuda do not have this very marked basal constriction. Most of them are moderately 

 long and stout, so that, in spite of the absence of the gigantic ones, the species usually 

 looks more spiny than A. gaussi, its appearance being well shown in Busk's figure. 

 Even when the gigantic spines of A. gaussi are broken off the shape of the remaining 

 basal portion is characteristic. A difference in the size of the basal avicularia of the two 

 species is noticeable, but, as many instances of variation in size within a species are 



t_j I i i ■ i .__J — i — i 



• 5mm 



Fig. 2. A-C. Amastigia benemunita (Busk). A. From St. WS 85, Falkland Islands. Large lateral basal avi- 

 cularium with part of proximal limb omitted. B. From St. 399, Gough Island. Smallest kind of lateral 

 basal avicularium (cf. A. nuda, fig. D). C. From St. 399. Gough Island. Median basal avicularium at 

 bifurcation. Mandible broken and foreshortened. D, E. A. nuda Busk. St. WS 84, Falkland Islands. 

 D. Lateral basal avicularium. E. Median basal avicularium at bifurcation. 

 Grooves into which mandibles fit are stippled, r. rootlet. 



known, this difference is probably not of systematic value. The distal wall of the fertile 

 zooecium of A. gaussi commonly bears a few teeth directed towards the ovicell (Fig. 1 C), 

 but they may be absent, or only represented by a single tooth. Such teeth have not 

 been seen in A. nuda. From his description of the scutum, the spines and the ovicell 

 it is clear that Hasenbank's material from Bouvet Island identified as A. nuda, belonged 

 to A. gaussi. 



There is some variation in the size of the frontal avicularia of A. gaussi. This is 

 most noticeable in the specimen from St. 167 which has some rather large ones. 

 A fragment from St. 599 has no scuta. 



