NO. 6 DECAPOD AND OTHER CRUSTACEA SCHMITT 21 



swimming pair, of legs is smooth, not armed with spinules. T. cxetas- 

 tica and most of its subspecies and varieties are also distinguished 

 from our species by the absence of these propodal spinules which are, 

 however, present in at least one variety of exetastica. All the cxetastica 

 forms differ from T. roosevelti and most if not all other Thalamitas 

 in possessing a small accessory tooth or spine on the outer side of 

 the first lateral, extraorbital tooth of the carapace. There is no trace 

 of such an accessory tooth in T. roosevelti. 



The basal antennal joint in our species is not wholly smooth, as it 

 has been described for T. alcocki, or low and almost indistinguishable, 

 as in imparimanus ; neither is the crest what one would in any sense 

 call denticulated, which it plainly is in T. investigatoris, exetastica, 

 gardineri, and kukcnthali, or armed with two large and prominent 

 teeth fused at the base as in T. tc unifies. In T. roosevelti the basal 

 joint, as described above, has a well-formed high crest visible in dor- 

 sal view, rather smooth appearing and at most no more than obscurely 

 denticulated, revealing, under the magnifier, small, low, irregularly 

 placed swellings or obsolescent small tubercles. 



With respect to the character of the basal joint and the armature of 

 its hands, T. roosevelti stands near T. alcocki; in the equality of the 

 chelipeds, proportions and general appearance of the front, carapace, 

 and lateral teeth, near T. gardineri. From the former our species 

 differs in having a relatively wider and deeper incision or sinus be- 

 tween the median lobes of the front, in having the fingers longer 

 instead of shorter than the palmar portion of the hand, and in being 

 armed with nearly twice as many or more than twice as many spinules 

 on the hinder margin of the propodus of the last pair of legs. From 

 T. gardineri our species differs by virtue of the fact that the submedian 

 lobes of the front overlap the median lobes in not having a truly or 

 plainly denticulated crest on the basal antennal joint, and in the rela- 

 tively longer fingers. 



Even if Miss Gordon's recently described T. malacccnsis (Bull. 

 Raffles Mus., No. 14, p. 176, figs. 2, 3, 1938) is to be considered one 

 of the species possessing a six-lobed front, the fact that the outer 

 lobes of the front are marked off from the submedian lobes by a mere 

 convexity of the anterior margin instead of a well-marked sinus or 

 incision sets it well apart from the one we have here described. 



Platypodia rotundata (Stimpson) 2$ 2$ 



Actea dovii Stimpson i$ 



Actea sulcata Stimpson ij 



M icropanopc xantusii (Stimpson) J c? 4? (3 ov ig-) 5 J uv - 



