382 PERCY SLADEN TRUST EXPEDITION 



Genus Trichorhina Budde-Lund (5), p. 293, 1908. 



The species of Trichorhina are tiny Isopods, not exceeding 2 — 3 mm. in length ; it is 

 only natui'al, therefore, that they should often escape being taken by naturalists, most 

 likely because of their likeness to young ones of other Isopods. 



The Sealark Expedition brought back a rather large number of specimens of a species, 

 which I class in this genus ; while most of the characters of this species are confluent with 

 the characters of the genus, given in the above-cited paper, the first pair of maxillae 

 presents a remarkable variation as to the teeth. 



Such differences as to this pair of the trophi I have also observed in other species 

 belonging to this group of Isopods, and I give a review of the species known by me, based 

 on these relations. 



Besides that the whole surface of the animal has a characteristic cover of tiny 

 setaceous scales, found on all the species ; an essential character may also be had from the 

 mandibles, the inferior seta having only two or three branches and the interior lobe of the 

 left mandible having a row of small papillae (Plate 21, fig. 18). 



Together with the small species fi'om the Siren Island, Cargados, brought back by 

 the expedition, I describe below another new species from Mauritius. Many years ago I 

 got a single small specimen of a species for which I could find no place in my system until 

 now ; it was brought to Denmark on a sailing ship carrying a cargo of sugar. 



Conspectus specierum. 

 Maxillae prioris paris lamina exterior : 

 a. Dentibus 4 + 5 (dentes 1, 2 apice fisso, dentes 3, 4, 5 serrati). 



1. Trichorhina minutissima, n. sp. 



2. Trichorhina micros, n. sp. 



aa. Dentibus 4 + 4 (dentes 1, 3 apice fisso, dentes 2, 4 integri). 



3. Trichorhina alhida Budde-Lund (5), p. 294, Taf. 17 , figs. 5 — 8. 

 aaa. Dentibus 3 + 4 (dentes 1, 2, 3 apice fisso, dens 4 integer). 



4. Trichorhina tomentosa Budde-Lund. 



5. Trichorhina quisquiliarum Budde-Lund. 



The two first species, Tr. minutissima and Tr. m,icros, I describe below. Of Tr. alhida 

 I have only seen one specimen, described in the cited treatise, and I cannot add any new 

 point, whereas I give below new descriptions of the two species Tr. tomentosa and Tr. 

 quisquilianum, which I earlier described and placed in the genus AUoniscus. 



Alloniscus papillosus Budde-Lund, Entom. Medd. 1893, p. 193 and AUoniscus 

 ambiguus Budde-Lund, ibid., p. 124, both species from Venezuela, which I referred 

 (Budde-Lund (5), p. 293) to the genus Trichorhina, are in the mouth-parts so different 

 from this genus, that I now place them in a new genus, Gedania, which has several 

 representatives, not yet described, in South America. However I should think that 

 the PlatyaiHhrus simoni DoUfus (Ann. Soc. ent. Fr., Ixii., p. 342) from Venezuela is a 

 Trichorhina. 



