8i 



Stat. 230. November 14. Lat. 3°58S., long. 128° 30' E. Hensen vertical net, from 2000 m. 



to surface. 2 immature specimens. 

 Stat. 243. December 2. Lat. 4°3o'.2 5., long. I29°25'E. Hensen vertical net, from 1000 m. 



to surface. 2 immature specimens. 



Distribution. — The specimens of this bathypelagic form examined by Sars were 

 taken in the tropical Atlantic and off Tristan da Cunha ; a specimen taken South of Australia 

 is mentioned by Willemoes-Suhm. Later the species has been captured by the "Investigator" 

 in the Bay of Bengal and by the Prince of Monaco several times in the Atlantic between 

 lat. 2 7°43'N. and 46°i5'N. 



Thysanopoda H. Milne-Edw. 



In his "Challenger" work Sars described 4 species, but since a good number have been 

 established by Ortmann, Illig and myself. In 1907 I examined the type-specimens of Sars 

 preserved in the British Museum (Natural History), with the following results. 



The type of T. obtitsifrons G. O. Sars (from Stat. 285) shows that his figures i and 2 

 on PL X\TII are somewhat misleading, because the rostrum, when seen from the side, is not 

 rounded off downwards, the front dorsal part of the carapace is adorned in a way different 

 from that shown on his fig. 2 and the lobe from the first antennular joint has a somewhat 

 other shape than seen on the same figure. In all these points his specimen agrees exactly with 

 my description (in Bull. Mus. Ocean. Monaco, N" 42, p. 20) of the same parts in T. vtilgaris 

 H. J. H. It may be mentioned that the front end of the carapace has no vertical, conical tooth 

 in his type-specimen, while a minute tooth or at least a vestige of a tooth is present in most 

 specimens of T. vulgaris^ which is to be cancelled as a synonym to T. obtusifrons G. O. S., 

 as the real characters used by me for separating the two forms are due to misleading details 

 in the description and figures given by Sars. — Another "Challenger" specimen from the 

 "Pacific" referred by Sars to T. obtusifrons is an immature T. crgjialis H. J. H. 



T. cristata G. O. Sars. — The type measures only 48 mm. in length from the end of 

 the rostrum to the tip of the telson, and the lower margin of the carapace has on each side 

 a conspicuous denticle near the posterior end. (In a future paper I will redescribe this species, 

 as I have some specimens from the Pacific). T. biprodtccta Ortm. is certainly only an immature 

 specimen, measuring 21 mm., of this species; I have compared a similar immature specimen 

 of T. cristafa from the Pacific with Ortmann's description and figure, 



T. inicroplithalina Cf. O. Sars. — Sars has mentioned two specimens, one taken by 

 Mr. LuMHOLTz and the other by the "Challenger"; the latter specimen, which must be considered 

 as the real type, is preserved in the British Museum. This specimen I found stained with 

 carmine and mounted on a glass-slide, thus in the state of preservation mentioned by Sars; in 

 order to examine it from all sides I dissolved the balsam. The examination gave the result 

 that the antennulae strongly disagree with the description of Sars, and that the specimen, the 

 "type", does not possess the denticle on the lower margin of the carapace described and figured 

 in the "Challenger" Report. Sars says that the specimen taken by Mr. Lumholtz enabled him 

 "to make out the distinctive characters with greater precision", but unfortunately he did not 



SIBOGA-EXPEDITIE XXXVI 



