242 



Among the specimens recorded, those of de Man from Amboyna are noteworthy for 

 their laro-e size, the length of carapace measuring nearly 13 mm., the breadth 18 mm. From the 

 same locality Zehntner records an even larger individual, which, like that of de Man, inhabited 

 the tube of a large Annelid (See note i and 5, p. 240). 



Dimensions in mm. ("Siboga" specimen): 



cT 



Fronto-orbital distance 3-~ 



Anterior margin of front i-55 



Length of carapace 5-5 



Breadth of carapace 8.4 



Length of meropodite ) j • r n ■ 1 i 3-5 



. > of second pair of walking legs { 

 Breadth of meropodite j ^ » t. | j.^^ 



Hexaplax Dofiein. 



1904. Hexaplax Doflein. Wiss. Erg. "Valdivia" Exp., Bd 6, Brachyura, p. 122. 



This remarkable deep sea genus is at first glance distinguished by the very large orbits 

 and hammer-shaped, well-pigmented eyes, further by its slender, elongate legs. Only a single 

 species is known. 



I. Hexaplax megalops Doflein. 



1904. Hexaplax viegalops Doflein. L. c, p. 122, pi. 31, f. 3 — 4, pi. 50, f. 7 (eye). 



1910. Hexaplax sp. Rathbun. K. Dansk. Vid. Selsk. Skr., 7. Raekke, Afd. 5, n^'4, p. 349, textfig. n. 



Stat. 12. 7°i5'S., ii5°i5'.6E. North of Bali. Depth 2S9 m. 3 cT (i juv.), 3 9 (i juv.). 

 Stat. 212. 5°54'.5S., I20°I9'.2E. West of Saleyer Island. Depth 462 m. i cf juv. 



A description of this interesting species would, to a great extent, be nothing but repeating 

 Doflein's diagnosis. This author knew only a single cf, and I am enabled now to state that 

 in the 9 the "musical ridge", consisting of a great many fine ridges placed on an elevated 

 ribbon, into which the pleural groove on the pterygostomian regions is transformed, is quite 

 as well developed as in the cf. Doflein compares this ridge with the "musical organ" of 6'r)^t>rt'<a: 

 (in which, however, as is well known, this appliance is situated at the inner surface of the large 

 chela and is rubbed against a crest at the ischiopodite of the limb), but to my mind it is better 

 comparable to what is found in Trizocarciiius Rathbun ^). The surface of the carapace is so 

 finely studded with closely-arranged granules as to give it the appearance of Ocypoda, under a 

 rather strong magnification. A strongly-concave cervical groove is faintly represented. The front 

 is strongly narrowed between the eye-stalks, widening anteriorlj-, with the angles rounded and 

 the anterior margin straight, but slightly notched in the middle; it is obliquely deflexed and 

 overhangs somewhat the antennulae, which are neatly folded up transversely; the antennae 

 reach as far laterally as the orbit. Owing to the very large, hammer-shaped eyes the orbit, 

 which is neariy entirely developed on the dorsal side of the animal, is greatly enlarged in its 

 distal half, so that a semi-circular notch is cut out in the supra-orbital margin. The eye-stalks 

 are freelv movable. 



i) Proc. C. S. Nat. Mus., v. 47, 1914, p. 117, textfig. i. 



94 



