204 ANCEIDJ:. 



the male is somewhat quadrate in form, having the 

 anterior margin more prominent than in the preceding 

 species; the upper surface of the head is more broadly 

 and regularly concave, and the mandibles are scarcely 

 more than one-third of the length of the head ; they are 

 curved, with the tip produced into a sharp tooth, below 

 which the inner margin is armed with about eight small, 

 sharp teeth. When shut, these mandibles project but a 

 small distance beyond the crenated fore margin of the 

 head. The antennae are about the length of the head, the 

 upper ones being shorter and considerably more slender 

 than the lower pair ; the latter pair are composed of 

 two strong basal joints, followed by a third joint, rather 

 longer than the second ; the fourth is still longer, rather 

 thickened at the tip, where it is armed with several 

 setae, and is followed by an eight-jointed flagellum. 

 The upper pair scarcely extends beyond the base of 

 the flagellum of the lower pair. The outer foot-jaws 

 are formed of a large basal joint, somewhat ovate-trun- 

 cate in form, affixed transversely by its base near the 

 posterior angles of the underside of the head ; the re- 

 mainder of the organ consists of four joints, forming a 

 broad, somewhat oval, flattened mass, affixed so as to 

 form an angle on the basal joint ; the first of these 

 four joints is small, and furnished with a strong seta 

 on its inner angle, whilst the remaining joints are 

 densely ciliated along the margin. The inner pair of 

 foot-jaws differs considerably from the same organs in 

 A. maxillaris, being formed of a large white, tumid, semi- 

 circular basal joint, having a small lobe at its inner 

 extremity, followed by four joints excessively delicate 

 and thin in their texture, and furnished on the outside 

 with long obliquely deflexed setae. The head is sepa- 

 rated from the first distinct segment of the body by a 



