AMASTIGIA 321 



4. Seta truly vibracular (i.e. asymmetrical at base with movement in more than two direc- 



tions) 5 



Seta an elongate avicularian mandible (i.e. symmetrical at base with opening and shutting 



movement only) ... ... ... ... ••• ••• ••• ••• ••• ••• 9 



5. Gigantic frontal avicularia present, branches (in part at least) with more than two series of 



zooecia ... ... ... ... ... ••• ••• ••• ••• ••• ••• ° 



Gigantic avicularia absent, branches biserial, except for median zooecium at bifurcation 



... 11. A. crassimarginata 



6. Gigantic avicularia on marginal zooecia only, numerous A. rudis 1 



Gigantic avicularia chiefly on inner zooecia, few 7 



7. True joints regularly present at bifurcation, crossing opesia of outer zooecium, scutum 



absent 5- A - kirkpatricki 



Joints, when present, of secondary "fracture" type, scutum present 8 



8. Branches 3- to 6-serial (except at base of colony), zooecia relatively short, scutum pear- 



shaped, spines on marginal zooecia 4 : 1 7- A. vibraculifera 



Branches 2- to 4-serial, zooecia relatively long, scutum with more marked distal and 



proximal lobes, spines on marginal zooecia 2 (rarely 3) : 1 ... 6. A. cabereoides 



9. Scutum absent, frontal avicularia rather conspicuous 10 



Scutum present, frontal avicularia not conspicuous n 



10. Frontal avicularia all unpaired 9- A. pateriformis 



Frontal avicularia paired on inner zooecia 8. A. antarctica 



11. Scutum with indented margin, branches 2-4 serial, cryptocyst wide ... 10. A. solida 

 Scutum with smooth margin and prominent truncate distal lobe, branches with 3-7, or 



more, series of zooecia, cryptocyst moderate 4. A. benemunita 



12. Spines small and inconspicuous, except a few extremely large ones constricted at base, 



zooecia and ovicells long ... ... ... ... ... ••• ••• 3- A. gaussi 



Spines usually fairly stout and conspicuous but none gigantic, zooecia and ovicells not 



particularly long ... ... ... ... ••• ••• ••• ••• ••■ ••• x 3 



13. Blade of scutum round, inner zooecia taking very small part in formation of basal wall and 



completely excluded in some branches, frontal surface correspondingly convex 



2. A. harmed 

 Scutum with long proximal lobe, inner rows contributing more to basal surface and never 



completely excluded, frontal surface flatter than in A. harmeri ... 1. A. nuda 



1. Amastigia nuda Busk. Figs. 1 B, 2 D, E. 



Amastigia nuda Busk, 18526, p. 40, pi. xxxvi, figs. 4, 5; Calvet, 1904, p. 7; part Harmer, 



i9 2 3. P- 33°. P 1 - xvii > fi g- 2 4- 

 Menipea benemunita Busk (part), 1884, p. 19 (specimens from Chall. St. 149, Kerguelen). 

 Station distribution. Sub- Antarctic: South Atlantic Ocean, Sts. WS 84, WS 85, WS 87. 

 Geographical distribution. Magellanic Region (Busk ; Calvet) ; Patagonian Shelf (Discovery) ; 

 Kerguelen (Harmer). 



Reasons are given (p. 322) for regarding the nearly related Australian form as a species 

 (Amastigia harmeri) distinct from A. nuda. 



One Challenger Kerguelen colony (87 . 12 . 9 . 68) is a typical specimen of A. nuda, and 

 additional typical material from the same station has recently been recognized 

 (35.3. 12. 1). Another Challenger colony from Kerguelen (87.12.9.75) approaches 

 1 For the species of Amastigia not discussed in this report see Harmer (1923). 



