& 



REPORT. ON THE CRUSTACEA MACRURA. lxxxv 



The Dendrobranchiata bare a few representatives in the ancient seas. Penseus 

 speciosus, Minister, from the "White Jura of Bavaria, is closely allied to the recent deep-sea 

 genua Genitalias; and Dusa monocera bears a miniature resemblance to Penseus monodon 

 of the Indian Ocean. The form of Aeger as restored in Salter and Woodward's Chart of 

 Fossil Crustacea is evidently supposed by them to be of the same genus, and Blaculea 

 sieboldi may belong to Penseus also. 



The recent genera that belong to this division, with the exception of the Sergestidse, 

 are mostly pelagic in their habits. In Japan the species Penseus canalicidatus is of 

 considerable size and is used as an article of food, a circumstance that would argue for 

 its frequenting water sufficiently shallow to be within the reach of ordinary fishermen, 

 but, in the record given, it is probable that many specimens are those of wanderers from 

 the deeper waters of their ordinary localities. Only one specimen of Gennadas is stated 

 to have been captured within 50 fathoms of the surface, whde others have been taken 

 beyond 3000 fathoms, and it is this deep-sea species that corresponds most nearly with 

 Penseus speciosus, Miinster; while Dusa monoceros of the same geological horizon bears a 

 tolerable resemblance to Penseus monodon, which is an inhabitant of less than 30 fathoms. 

 With the exception of a few species, such as Petalidium, that have been dredged, 

 almost all the Sergestidse have been taken within 50 fathoms of the surface, and none of 

 these have been recorded as having been found in a fossd condition. 



The division Phyllobranchiata is still more feebly represented. Tropifer Isevis, 

 Gould, 1 appears to me to approximate more nearly to the genus Pontocaris of the 

 Crangonidas than, as supposed by the author, to the genus Nephrops or Scyllarus, in 

 consecmence of the lateral position of the ophthalmopoda. The absence of any rostrum, 

 and the presence of the ophthalmopoda as short and spherical bodies at the outer 

 angles of the frontal margin of the carapace, bear comparison with Pontocaris, the 

 carapace of which is longitudinally traversed by carina, and transversely divided by a 

 cervical fossa. In the fossil specimen the ophthalmopoda are at the extreme fronto- 

 lateral angles of the carapace, while in Pontocaris pinnata (PL XCI. fig. 1) the fronto- 

 lateral angles project on the outer side of them, but in the younger forms of Crustacea 

 the ophthalmopoda are moi'e in accordance with the condition seen in the fossil 

 specimen. 



Urodella agassizii, Oppel, from the Upper White Jura of Bavaria, may find its 

 congener in the genus Crangon of recent times, but the pereiopoda are not sufficiently 

 figured in clear detail for a fixed opinion to be given. 



The common Shrimp that so abundantly frecraents the shores of Europe, lives generally 

 where the sand is fine and most abundant. They swim about in the shallow water that 

 precedes the incoming tidal wave, or when at rest sink to the bottom and partially bury 

 themselves in the sand, first by wriggling out a depression with their legs and bodies, 



1 Proc. Zool. Soc. Lond., vol. xiii. p. 360, fig. 1. 



