76 DR. J, Q. DE MAN ON THE PODOPHTHALMOTJS 



dividuals. In most examples tlie ridge on tte basal joint of the 

 outer antennae is provided with a row of very short, small spines ; 

 in some specimens, however, as in the largest male from Elphin- 

 stone Island, these spines coalesce into a denticulated laminiform 

 crest, such as that described by Stimpson in the Japanese Thala- 

 mita picta ; but in other individuals again this ridge is only 

 armed with some acute granules oE unequal size. 



As the internal lobes of the upper orbital margin (outer frontal 

 lobes) have probably a constant form in each species, it may be 

 possible by them to distinguish the different species of this 

 difficult genus. Thus these lobes are nearly straight in Thalamita 

 Danes, Stimps., but somewhat arcuate in T. prymna. 



In all these specimens, even in the small individuals from King 

 Island and in the very young male from Elphinstone Island, the 

 outer surface of the hand is armed with a granulated crest between 

 the elevated ridge, near the inferior margin, which runs on to the 

 immobile finger and the spines of the upper surface. They thus 

 differ in this character from the Eed-Sea individuals described 

 by me some time ago under the name of Thalamita jprymna (Notes 

 from the Leyden Museum, vol. ii. 1880, p. 180) ; for in the latter 

 the crest does not occur, when they are less than 45 millim. broad, 

 but only gradually begins to appear when they have attained 

 that size. The Mergui specimens and those from the Eed Sea, 

 therefore, are either varieties of one species, or they belong to 

 different forms. In the latter case, I propose to distinguish the 

 Hed-Sea specimens as Thalamita picta, a species still very im- 

 perfectly known and insufficiently characterized. One character 

 mentioned as distinctive between these two forms, viz. the occur- 

 rence of an acute prominent crest on the basal joint of the 

 external antennae, occurs sometimes in specimens of Thai, prymna, 

 as I have described above. 



Thalamita prymna is found in the Indian Ocean and the 

 Malayan Archipelago (Padang, Timor, Halmahera). It has also 

 been recorded from the coast of New Caledonia, the Loo-Choo 

 Islands, and Japan. 



The occurrence in the Eed Sea of the typical T. prymna, 

 as now characterized, is a little doubtful. 



53. Thalamita spinimana, Dana. (PI. IV, fig. 7.) 

 Thalamita spinimana, Dana, United States ExpL Exp., Crust, part i. 



