Page:Transactions NZ Institute Volume 15.djvu/136

spines and a short seta. Abdomen slender, first joint about equal in length to the two following: last segment much shorter than preceding; caudal segments nearly as broad as long. Longest caudal seta equalling the abdomen in length; outer and inner very short. Length, ¹⁄₃₃ of an inch.

Hab. Tomahawk Lagoon, near Dunedin (several specimens).

The above description is almost that of Dr. Brady; my specimens differ from his in hardly any respect but the form of the caudal forks. Any other differences are unimportant.

"Body much compressed. Dorsal margin very convex. Head and last thoracic segment very large, produced ventrally and approximating so as to give a more or less circular outline to the animal. Abdomen very short. Head united with the first thoracic segment. First pair of antennæ elongated, 6- or 8-jointed; second pair 3-jointed, and bearing a small 1- or 2-jointed secondary branch, last joint clawed. Mandible palp 1-branched; maxillar palp elongated, 2-jointed. First foot-jaw slender, 3-jointed; second much elongated, 2-jointed, and forming a strong grasping hand. First pair of feet not prehensile, 2-branched, each branch consisting of a single joint; second, third, and fourth pairs with both branches 3-jointed. Fifth foot in the female composed of two, in the male of one, joint. Integument excessively tough and coriaceous, usually cellular or areolated."

The animals forming this genus differ from all others of the family to which they belong in being laterally compressed. In fact their appearance is so remarkable that, until their structure is examined in detail, their affinities would never be suspected. Other prominent characteristics of the genus are the relatively large posterior foot-jaws, and the strongly-marked punctations of the integument. The occurrence of the genus in these seas is very interesting, as hitherto it has not been observed, as Brady remarks, outside the European area.

1. A. clausii, n. sp. Pl. V., fig. 1.

First segment of body greatly produced downwards and posteriorly to an almost acute point on each side; four succeeding thoracic segments only about one-fourth the depth of the first, and together hardly exceeding it in length; two anterior abdominal segments large, produced downwards, the first forming a wide expansion, which nearly meets the first body segment, the second ending in an obtuse point; remaining abdominal segments very much abbreviated; caudal setæ minute. Eye large, very difficult to distinguish satisfactorily. Anterior antennae 6-jointed, about as long as the first segment of the body; first and second joints subequal, third about half