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



refer Professor Dana's Cyioridina gibbosa to the same group. These, with a European 

 species ah-eady descril:)ed by myself (Philomedes folini) , comprise all the known members 

 of the genus. 



1. Philomedes gibbosa (Dana), (PI. XXXIX. figs. 12-17). 



Philomedes gibbosa, Dana, Crust., United States' Exploring Expedition, p. 1295, pL xci. fig. 4, a-c. 



Shell membranaceous, pale yellowish-brown, seen from the side (fig. 12), elongated, 

 much higher in front than behind, height equal to more than half the length ; beak 

 consisting only of a small acuminate process situated about the middle of the anterior 

 margin, below which is a very shallow curved notch ; anterior extremity broad and 

 obliquely truncated, rather concave above, and convex below the beak, fringed below the 

 middle and at the ventral angle with a series of rather long curved setse ; posterior 

 extremity tapering, narrow, forming a rather upturned beak-like process ; dorsal margin 

 rather boldly arched, ventral gently convex ; seen from above, oblong-ovate, widest in the 

 middle, tapering and comj)ressed towards the posterior extremity ; anterior extremity 

 obtusely, posterior very acutely pointed, width equal to half the length. Anterior 

 antennae (fig. 14) five-jointed (?), fourth joint bearing a moderately long seta which has 

 near its base, and arranged in a pectinate manner, a series of six marginal setae ; the last 

 joint is very small, and has five apical setse, two long and three short. Secondary branch 

 of posterior antenna (fig. 1 5) rudimentary, consisting only of three short setae. Length, 

 l-20th of an inch (l"3 mm.). 



Taken in the surface-net, Zebu Harbour, Philippine Islands. 



[PI. XXXIX. figs. 12-17. 12 Carapace of male seen from right side, 13 the same from 

 above (magnified 50 diameters), 14 anterior antenna {a, a eyes), 15 secondary branch of 

 lower antenna, 16 mandibular foot, 17 first maxilla.] 



2. Philomedes tvyville-thomsoni, n. sp. (PI. XXXVI. fig. 1, a-c). 



Shell stout and calcareous ; seen from the side, broadly subovate, greatest height situ- 

 ated in the middle and equal to fully two-thirds of the length ; notch shallow, beak 

 rounded ofi" and obtuse ; anterior extremity above the notch broad and obtusely 

 angulated, gently curved below, posterior produced in the middle into a short, wide and 

 obtusely-rounded prominence ; dorsal margin well and evenly arched ; ventral somewhat 

 flattened in the middle but curved upwards at the ends ; seen from above, the shell is of 

 irregularly oval shape with obtuse extremities ; the lateral margins are curved and some- 

 what irregularly sinuous in front of the middle where they sink abruptly forming two 

 projecting lateral wings, thence they continue with a gentle curve backwards and are 

 twice deeply sinuated near the hinder extremity ; the greatest width is in the middle and 

 is nearly equal to the height ; end-view extremely irregular in outline, showing two 



