CRUSTACEA. 537 



42. Tetralia cavimanus, Heller. 



Seychelles, 4-12 fms. (No. H»4), nine specimens; Etoile Island, 

 13 fms. (No. 191), five specimens. 



Specimens are in the British-Museum collection from Ilodrigucz 

 (H. H. Slater); Ked Sea, Gulf of Sue/ (JR. MacAndrew) ; Daedalus 

 Shoal (Lt.-Col. Playfair); Fiji Islands, Ovalau, Totoya i //. M.S. 

 1 Herald'); and others without special locality. In some specimens 

 there is a very distinct transverse hand of darker colour on the front ; 

 in others it is scarcely, or not at all, discernible. The pit on the 

 outer margin of the hand near the wrist, whereby Dr. Heller dis- 

 tinguishes this species from T. glaberrima (Herbst), varies greatly 

 in depth : ordinarily, in well-grown and even in smaller examples, 

 it is deep, well defined, and clothed with hair; but in other rather 

 small specimens it is so shallow as scarcely to he distinguishable 

 and devoid of hairs. Ordinarily, in adult males, the lower finger of 

 the larger chelipede is more or less strongly dentated on its inner 

 margin, and there is scarcely any interspace between the fingers 

 when closed ; but in two very dark-coloured males from the 

 Seychelles, in the ' Alert ' collection, the fingers are scarcely 

 dentated and are strongly arcuated, meeting only at the tips. A 

 similar variation occurs in a male from the collection of II. M.S. 

 ' Herald,' which, on account of the entire absence of the palmar 

 pit, is referred to T. glaberrima. 



I think the T. heterodactyla of Heller is probably a mere variety 

 of T. cavimanus, to which species (if, indeed, it he distinct from 

 T. glaberrima) nearly all the specimens of this genus in the Museum 

 collection must he referred. Although several species of this genus 

 have been described, of earlier date than T. cavimanus, by Dana, 

 Stimpson, and Lucas, by none of these authors, I believe, is any 

 mention made of the suhbasal pit on the palm of the chelipede 

 which is so characteristic of T. cavimanus. 



pedes, I am not even sure whether it should be referred to the Cyclometopa or 

 to the Catometopa. In most of its characters, however, it nearly resembles a 

 species of Trapezia, differing mainly in the more elongated convex and regu- 

 larly hexagonal carapace and in the dactyli of the ambulatory legs. The cara- 

 pace is smooth and slightly but regularly convex ; the front is about half the 

 greatest width of the carapace, and is divided by three notches into four promi- 

 nent triangular teeth, the median notch being the deepest ; there is also a small 

 spinule or tooth at the inner supraocular angle, and a short spine at the widest 

 part of the carapace at the angle where the antero-lateral and postero-lateral 

 margins unite. The endostome or palate has faintly indicated longitudinal 

 ridges. The postabdomen is shaped nearly as in Trapezia. As in Trapezia, the 

 inner and inferior margin of the orbit reaches to the front and excludes the 

 antenna;, and bears a strong spine; the basal peduncular joint of the antenna? 

 is rather short, and the penultimate joint reaches to the frontal margin. The 

 outer inaxillipedes present nothing remarkable, having a truncated merus-joint, 

 and exognath reaching to its extero-distal angle. Of the legs only the third and 

 fourth are present on each side ; these are rather longer and slenderer than in 

 Trapezia, and the three terminal joints are somewhat hairy ; the dactyli are 

 armed on their inferior margin with about half-a-dozen spinules, which increase 

 successively in length. Colour (in spirit) yellowish white. Length of carapace 

 nearly 4i lines (9 miliini.), breadth nearly 5 lines (lU millim.). 



