DUEIIS'G THE 'CHALLENGER' EXPEDITION. 91 



abruptly undulated outline. Seen from above, the outline is compressed, subclavate, 

 sides nearly parallel but slightly converging towards the obtusely-pointed front ; 

 posterior extremity wide and subtruncate, greatest width considerably less than half 

 the length. Surface of the shell covered with numerous subrotund pits and sparingly 

 setose. Coloi;r light brown. Eyes large and black. Length 1"9 millim. 



Secondary branch of the antenna (fig. 14) three-jointed and strongly prehensile ; 

 basal joint short and bearing several setae, one of which is long and plumose ; second 

 joint much elongated, and having two long setae in the middle of the external margin ; 

 third joint also long, curved, with a denticulated external margin, a single long seta at 

 the base, its apex rounded, crenulated, and slightly split up in a multifid fashion. 



Apex of the vermiform appendage (fig. 15) having its upper process armed with five 

 slender curved spines ; lower portion rounded, obtuse, and toothless. Caudal laminae 

 (fig. 16) bearing three principal ungues and six very small spine-like setae : the first 

 five setae are quite minute, then follows a strong curved unguis of moderate size ; a 

 sixth small seta intervening between it and the following unguis, which is twice as long 

 as the preceding ; the last unguis is still longer and, like its neighbour, has a spinulose 

 margin. 



Female. — "Valves somewhat larger and much more circular in outline, with the beak 

 small and very slightly produced ; oral notch nearly rectangular ; height about three- 

 fourths of the length ; easily distinguished externally from the male by the small size 

 of the eye-spot. Eyes reddish." 



I am indebted to Professor G. M. Thomson, of Otago, for specimens of this 

 interesting species, which was taken by him " swimming actively in the rock-pools 

 on the Taieri Beach." The specimens sent to me were all males. I have therefore 

 quoted Prof. Thomson's description of the female shell. 



Philomedes coretjgata, n. sp. (Plate XVI. figs. 17-21.) 



Shell very tumid: seen from the side (fig. 17) subrhomboidal, highest about the 

 middle, height equal to two-thirds of the length ; the dorsal and ventral margins 

 markedly convex ; anterior extremity narrowed and rather oblique, beak blunt and not 

 very prominent, notch very shallow ; posterior extremity evenly rounded. Seen from 

 above (fig. 18), the outline is subpentagonal, greatest width situated behind the middle 

 and equal to four-fifths of the length ; the anterior margin is rounded off but extremely 

 broad and almost subtruncate, the posterior margin slopes very abruptly and with an 

 irregularly sinuous curve from the widest point, and terminates in a very broad obtusely 

 rounded median process; the lateral margins converge very slightly and in sinuous 

 fashion towards the wide anterior extremity. The surface of the shell is much 

 wrinkled and pitted, and slightly hispid with short distant hairs. Colour reddish 

 brown. Length 1*4 millim. 



The sculpturing and general outline of the shell as shown in the lateral view (fig. 17) 



