86 



more clumsy than in T. microphthalma and more similar to T. acutifrons, but not quite as 

 large, as the latter measures 35 — 43 mm., while the largest specimen of T. orientalis seen by 

 me (the female from "Siboga") is 38 mm. and an adult male (from the Pacific) only 23 mm. 

 The front end of the carapace (figs. 2 a — 20) is shaped quite as in T. acutifrons \ no denticle 

 on the lower margin near the posterior end. Eyes dark brown or brownish black as in T. 

 microphthalma. The lobe from the first antennular joint (fig. 2c) nearly as in T. acutifrons, 

 but its end is, seen from the side, distinctly a little more produced, acuminate, but not quite 

 as much as in T. microphthalma. The antennal squama reaches beyond the end of the upper 

 and inner produced part of second antennular joint as in T. acutifrons. The terga of fourth 

 and fifth abdominal segments very slightly acuminate at the middle of the posterior margin as 

 in T. microphthalma. 



As already stated, the copulatory organs of the three species show excellent specific 

 differences. In all three forms the median lobe is long and terminates in an acute, small lobe, 

 its lateral process is long and distally curved, while the additional process is short, oblong, 

 very thick, but otherwise showing some differences; furthermore the inner lobe possesses the 

 spine-shaped process, while the proximal process is thick at the base, moderately slender from 

 the basal portion to the acute apex, and with some teeth on the outer side near that end. 

 But the terminal process and the length and curvature of the proximal process show excellent 

 specific differences. 



In T. acutifrons the terminal process is somewhat short, with its distal fourth tapering 

 and slightly curved with the end acute ; the proximal process is more than twice as long as the 

 terminal, and its distal three-fourths very moderately curved. In T. microphthalma the terminal 

 process is rather long, increasing somewhat in breadth at the end, which is turned backwards 

 in a most peculiar way, showing a transverse row of saw-teeth just behind the flatly arched 

 terminal surface: the proximal process is only a little longer than the terminal, not reaching its 

 end and very moderately curved. In T. orientalis the terminal process is somewhat long and 

 strong, tapering feebly to the broadly rounded, unarmed end; the proximal process is very 

 long, but not quite twice as long as the terminal, bent strongly inwards at the end of the 

 proximal fifth, with the distal four-fifths very, nearly semicircularly, curved. 



Very young Specimens. — Two such specimens (from Stat. 143) measure about 

 10 mm. in length. The carapace has a small but very conspicuous denticle on the lower margin 

 a little in front of the posterior end; anteriorly (fig. 2 cl) it is more produced than in the adults, 

 the frontal plate forming a triangle a good deal broader than long, with the lateral margins 

 straight ancl the apex a little produced, acute; the dorsal carina is well developed. The eyes 

 (fig. 2 cl) are very light brownish, considerably higher than broad, divided into two areas by 

 an impression a little above the middle. The lobe from first antennular joint in the main as 

 in the adult. The distal part of the telson as in the adults, the pleopods setiferous, but the 

 posterior pairs of thoracic legs being lost it is impossible to state anything as to their degree 

 of development. 



Larvs. One of the larva; from Stat. 143 measures 5.7 mm., and being sure that 



it belongs to this species I give five figures (figs. ie — 21). The carapace has a very long 



