REPORT ON THE AMPHIPODA. 1489 



Amphithyrus sp. 



Length. — One-tenth of an inch. 



Locality. — September 13, 1874, Arafura Sea ; lat. 8° 18' S., long. 135° V E.; surface; 

 surface temperature, 79°. One specimen, male. 



Remark. — I forbear to give a name to this interesting little species, as there is not 

 time at my disposal to give an adequate description of it. 



Amphithyrus bispinosus, Claus. 



1879. Amphithyrus hispinosm, Claus, Die Gattungen imd Arten der Platysceliden, p. 15. 

 1887. „ ,, Bovallius, Systematical List of Amph. Hyper., Bihang till K. 



Svensk. Vetensk.-Akad. Handl., Bd. 11, No. 16, p. 48. 

 1887. „ „ Claus, Die Platysceliden, p. 41, Taf. vi. figs. 4-16. 



The Challenger specimen clearly and closely agrees with the description and figures 

 of the species given by Claus. The species is well marked by the large laterally 

 projecting spine-like process of the side-plates of the third peraeopods. The side-plates, 

 with the exception of those of the fifth perseopods, have their upper boundary distinct ; 

 the lower front angle in the first pair is directed a little forwards, and is almost acute ; 

 the postero-lateral angles of the first three pleon-segments are rounded. The sculpture 

 of the integument, though in many parts showing hexagonal markings, in others takes 

 the form of more or less parallel wavy lines. 



Tfie Eyes are separated by a central space which is broad over the acute point 

 separating the upper antennae. 



The Lower Antennse in this specimen are not tightly folded as in the fully adult 

 male ; the third (first free) joint of the peduncle is more or less pear-shaped ; the next 

 or fourth joint is more than twice as long, sinuous ; the fifth is straighter and rather 

 longer than the fourth, each having a subapical spinule, but being otherwise smooth- 

 edged ; the flagellum consists of one serpentine joint, longer than the last joint of the 

 peduncle. 



The Mouth Organs so far as observed were in agreement with Claus' figures ; seen 

 from below they exhibit a small Epistome occupying the space between the bases of the 

 two mandibular palps ; the upper margin is flat, the lateral margins convex, while the 

 lower border shows a curved emargination, overarched by a much larger triangular 

 depression of the surface. The mandibular palps in our specimen are sinuous, the joints 

 undeveloped. 



First Gnathopods. — First joint straight, widening a little distally, rather longer than 

 the remainder of the limb ; second joint with a spinule at the hinder apex ; the three 

 following joints subequal in length to one another, the wrist rather the longest by reason 



(ZOOL. CHALL. EXP. PART LXVII. — 1888.) XXX 187 



