546 THE VOYAGE OF H.M.S. CHALLENGER. 



Sir Walter Elliot's collection, from a specimen obtained at Waltair on the coast of 

 Madras, which corresponds with this form, shows the animal to be of an orange colour 

 with a broad dark crimson stripe on each side of the median line from head to tail, and 

 one across the rhipidura. 



Atyhens cristidigitus, n. sp. (PI. XCVII. fig. 3). 



Carapace having a slender rostrum. Orbital lobes dorsally elevated above the 

 median crest and armed anteriorly with a small tooth that does not reach so far as the 

 apex of the rostrum. 



The first pair of antennae has the upper branch but little longer than the peduncle, 

 robust, truncate, without any slender terminal flagellum. The lower branch is slender 

 and much longer than the upper, being two-thirds the length of the animal The 

 stylocerite is broad, flat, and tipped with a minute, slender, sharp tooth. 



The second pair of antennae is as long as the animal, and supports a scaphocerite that 

 reaches to the extremity of the peduncle. 



The first pair of pereiopoda is very unequal, the right being the greater in most of 

 our specimens, and is very large and irregular in form. The propodos is rather more 

 than half the length of the animal, it has a deep notch on the upper surface and a 

 corresponding one on the lower, at the base of the dactylos ; on the upper margin there 

 is a sharp tooth, and a second and stronger one is placed a little posterior to it. The 

 dactylos is broad, obtuse, obliquely articulated, and only one-fourth the length of the 

 palm. The left (fig. 3k) has the propodos about two-thirds the length of the right, 

 and has a notch on the upper and lower margins opposite to each other ; on 

 the upper side anterior to the notch, close behind the dact}doid articulation, is a 

 strongly projecting tooth or sharp angle ; the pollex is straight and smooth, the 

 dactylos is straight on the inner or proximal margin and arched on the outer side, on 

 which a thin marginal crest is continuous from the base to the apex. This crest 

 is so peculiar, that I have derived the specific name of the animal from it. The second 

 pair of pereiopoda is slender ; the third and fourth pairs have the meros armed with a 

 strong tooth on the lower distal angle. 



The fifth pair is more slender and shorter than the preceding, has no tooth on 

 the meros, and terminates in a simple, pointed dactylos, resembling those of the two 

 preceding pairs. 



The pleopoda are slender and the telson is broad, slightly tapering, distally rounded, 

 fringed with hairs, and armed on the dorsal surface with two small equidistant spines on 

 each side of the median line. 



