AMMOTHEIDAE 95 



KEY TO THE DETERMINATION OF THE ANTARCTIC AND 

 SUB-ANTARCTIC SPECIES OF AMMOTHEA 



I. Chela large and perfect in the adult as well as in immature specimens [palp nine-ji)inted ; 

 transverse body ridges high; species of large size]. 



A. Proboscis sub-cylindrical, rather slender and much curved, equal to trunk; chela 

 slightly longer than scape ; palpal segments 2 and 4 subequal ; second tibia the longest 

 segment; no large spines on ventral margin of propodus A. striata (Mobius) 



B. Proboscis straight, massive and somewhat pyriform, not quite three-fourths of trunk; 

 chela half as long as scape ; palpal segment 4 rather longer than 2 ; femur tiie hmgest 

 segment; two spines on proximal ventral margin of propodus, the larger just over 

 one-third of main claw A. gigantea, n.sp. 



II. Chela large and perfect in immature specimens, imperfect and much reduced in adults. 

 A. Palp eight-jointed [transverse body ridges prominent, each rising in centre to an 

 acutely conical process; two spines on proximal ventral margin of propodus; second 

 tibia the longest segment] . 



I. Proboscis not quite two-thirds of trunk, bluntly conical ; chelophore half as long as, 

 palp rather longer than, proboscis; cephalic segment approximately equal to the 

 sum of the three succeeding segments ; larger spine on propodus scarcely half as long 



as main claw; male genital openings present on all four legs A. tetrapora, n.sp. 



[II. Proboscis slightly shorter than trunk, styliform; chelophore one-third of, palp 

 rather shorter than, proboscis ; larger spine on propodus half of main claw ; cephalic 



segment equal to the sum of the two succeeding segments ^. sp.? St. WS 216I] 



III. Proboscis rather longer than trunk, styliform; chelophore scarcely one-third, palp 

 not more than two-thirds, of proboscis; larger spine on propodus four-fiftiis of 

 main claw; cephalic segment scarcely equal to the sum of the two succeeding 



segments A. longispim, n.sp. 



B. Palp nine-jointed [and longer^ than proboscis]. 



I. Transverse body ridges prominent, each, as a rule, rising in centre to at least the 

 height of the ocular tubercle. 



A. First tibia the longest segment; propodi of first and second markedly different 

 from those of the third and fourth legs [claw almost two-thirds of propodus ; 

 proboscis scarcely as long as trunk, sub-cylindrical with a slight median 

 constriction] A. spinosa {Hodgson) 



B. Second tibia the longest segment; propodus similar for all four legs. 



1. Palpal segments 5-8 serrated ventrally [segments 2 and 4 subequal; 

 proboscis at least as long as trunk, pyriform; 4-6 small spines on proximal 

 half of ventral margin of propodus] A. minor (Hodgson) 



{A. gracilipes, Bouvier) 



2. Palpal segments 5-8 cylindrical, not serrated ventrally. 

 a. Proboscis not exceeding three-fourths of trunk. 



i. Proboscis sub-cylindrical; chelophore two-thirds of proboscis [palp 

 longer than proboscis, segments 2 and 4 subequal; 3-4 spines on 

 proximal half of ventral margin of propodus, the larger just over 



one-half of claw which is two-thirds of propodus] A. calmani, n.sp. 



{A. striata} Caiman) 



1 This form is inserted here as the palp is apparently not quite normal and might prove to be eight-jointed. 



2 Palp not quite normal— may be longer or at least equal to proboscis in A. sp.? St. WS 216. 



