184: G. 0. SARS, 



ponding segments, and having the distal edge densely setiferous; 1st pair 

 somewhat narrower than the succeeding pairs and slightly curved; 4tli i)air 

 not fully as deep as the preceeding pairs, and having the distal edge ol)li- 

 quely truncated; the 3 posterior pairs comparatively small and of normal 

 appearance. Last pair of epimeral plates of metasome obtusangular. Eyes 

 small, rounded, with dark pigment. Superior antennae somewhat exceeding 

 in length Vg of the body, and rather densely setiferous, 1st joint of the 

 peduncle comparatively large, flagellum nearly twice the length of the i)ed- 

 unclc, and composed of numerous articulations; accessory appendage only 

 represented by an extremely small nodule carrying 2 delicate bristles. In- 

 ferior antennae but little more than half the length of the superior, and of 

 normal structure. Gnathopoda in female rather feeble, subequal, propodos 

 in both pairs about the length of the carpus and scarcely broader, palm 

 well detined, being in the anterior ones more oblique than in the posterior; 

 those in male somewhat stronger, with the propodos considerably expanded, 

 forming below a rouuded spiuiferous lobe defining the deeply concaved 

 palm, dactylus strong and curved. Pereiopoda rather slender, and having 

 their outer part edged with numerous fascicles of bristles, basal joint of 

 antepenultimate and penultimate pairs comparatively narrow and tapering 

 distally, tliat of last pair considerably more expanded, with the greatest 

 breadth below the middle. The 2 anterior pairs of uropothi having the rami 

 subequal and falciform in shape; last pair much shorter than the former, 

 with the outer ramus somewhat longer than the basal part, and provided 

 with a few fascicles of small bristles. Telson extremely small, scarcely half 

 as long as it is broad at the base, outer part narrowed and having in the 

 middle a short cleft. Length of adult female 20 mm., of male 25 mm. 



RemarJ^s. — This remarkable Amphipod cannot be confounded with 

 any other form, exhibiting, as it does, a most peculiar appeai-ance by the 

 extremely stout and compact body and its strange spinous armature. It may 

 however be observed, that some of the species oi Allorcliestcs (or HyaUdla) 

 found in the Titicaca Sea and described by Mr. W. Faxon, exhibit a some- 

 what analogous armament of the body. Especially is this the case with the 

 species named Allorchestes armata. But liere the lateral spines are not 

 formed by the segments themselves, but by tlie greatly extant coxal plates, 

 the most prominent lateral spines being represented by the 4th pair of coxal 

 ]ilates. It is evident that this peculiar armature of the body, occui-ring in a 

 similar mode in so widely different forms, must have some significance for the 

 animal. I believe that these laterally projecting acute spines may serve as 

 a means of defence, whereby the animal, which apparently is far less active 

 than the other Gammaridae, becomes partly secured against the attack of 



$lJ3.-MaT. CTp. 1S4. A 



