TEEEESTKIAL ISOPODA OF NEW ZEALA.Ni). 181 



Specific characters. — Body convex, surface with short, l)lLiiit, scattered spines, especially 

 on the margins of the metasomc and on the appendages. Cejihalon witli the front 

 rounded, with raised frontal margin, a little depressed in middle, a deep groove on each 

 side interior to the prominences I)earing the eyes. Inferior mai-gin of first segment of 

 niesosome thickened, not incised. Posterior angles of the first four segments of mesosome 

 sidjquadrate, those of tiie last three produci^d backwards, subacute. Epimeral positions of 

 third to fifth segments of metasome large and contiguous, and containing the outline of 

 the metasome. Terminal segment very short, convex, slightly pointed between the bases 

 of the uropoda. Eyes very large, on two crescentic prominences, occupying whole lateral 

 border of the cephalon ; ocelli very numerous, arranged in four or five longitudinal rows. 

 Antenna; with all the joints covered Avith short blunt spines, fiagellum about as long as 

 preceding joint ; its terminal fourth joint minute. Uropoda projecting beyond the 

 terminal segment, and pretty accurately filling up the space between tlie epimera of the 

 fifth segment ; outer part of base produced into a rounded lobe, outer branch inserted 

 on the inner portion of the distal margin, spatulate, extending a little beyond tbe 

 produced portion of the base ; inner rami, arising from the under surface of the base, 

 far in front of the outer, slender, scabrous ; apex uith a long bristle, which is visible in 

 dorsal view. 



Colour light grey, with irregular black markicgs; during life sometimes coloured 

 as in Hcypliux oniatus. 



Length about 10 mm. 



Habitat. — Sandy beaches in New Zealand. 



BemarLs. — This species is frequently found on sandy beaches in company with 

 IScyphax urnatiis, and is very similar to tliat species in colour and habits, so tliat Dana 

 thought it was perhaps the young of Scyjihaa;. From what has been already said, it is 

 clear that this is not the case, and that the two are perfectly independent ; I h ive 

 mature males of both species. When pursued, Actcecia euchrou rolls itself into a ball, 

 and is then tilmost indistinguishable from a grain of speckled sand ; under similar 

 cii'cumstances Hcypliax oniatus crouches down closely on the sand, and is then equallv 

 diificult to peicei\e. I liave always found these two species on the open sands and 

 never under cover, and the large and well-developed eyes that they both possess have 

 probably been developed in connection with their exposed mode of life. 



The extremities have the usual three joints, though the articulations are not always 

 easy to see ; the last joint is tapering and bears a few setae. The mouth-parts show a 

 close general resemblance to tliose of Scyphax, the mandibles and first maxiUaj beiu"' 

 very similar; the appendage figured by Thomson as the inner lobe of this maxiUa is 

 really the second maxilla, which has the outer margin angularly produced near the base, 

 and the outer lobe at the apex very small and indistinct. In the maxillipedes the 

 ischium is distinct, but the following joints are all fused into a triangular plate with 

 lobes on the inner margin indicating the separate joints ; the masticatory lobe is small 

 and obliquely truncate, about half as long as the terminal portion of the maxillipede. 

 The legs have the dactyla short and stumpy-looking; the dactylar seta with distal half 

 thickened and presenting a stippled appearance. 



SECOND SERIES. — ZOOLOGY, VOL. VIII. 20 



