CLASSIFICATION 277 



Japan; and (iii.) T. hoeveni, Pocock ( = L. MOLUCCANUS, Van 

 der Hoeven), found in the Moluccas. 



Genus B. Carcinoscorpius with one species, C. rotundicauda 

 (Latreille) ( = L. ROTUNDICAUDA, Latreille). It occupies a more 

 westerly area than T. gigas or than T. tridentatus, having been 

 recorded from India and Bengal, the Gulf of Siam, Penang, the 

 Moluccas, and the Philippines. 



With regard to the affinities of the group it is now almost 

 universally accepted that they are Arachnids. The chief features 

 in which they differ from other Arachnids are the presence of 

 gills and the absence of Malpighian tubules, both being features 

 associated with aquatic life. As long ago as 1829 Straus- 

 Diirckheim emphasised the points of resemblance between the 

 two groups, and although the view was during the middle of the 

 last century by no means universally accepted, towards the end 

 of that epoch the painstaking researches of Lankester and his 

 pupils, who compared the King-crab and the Scorpion, segment 

 with segment, organ with organ, tissue with tissue, almost cell 

 with cell, established the connexion beyond doubt. Lankester 

 would put the Trilobites in the same phylum, but in this we do 

 not follow him. With regard to the brilliant but, to our mind, 

 unconvincing speculations as to the connexion of some Limulus- 

 like ancestor with the Vertebrates, we must refer the reader to 

 the ingenious writings of Dr. Gaskell, 1 recently summarised in 

 his volume on " The Origin of Vertebrates," and to those of 

 Dr. Patten in his article " On the Origin of Vertebrates from 

 Arachnids." ~ 



Fossil Xiphosura. 3 



Limulus is an example of a persistent type. It appears first 

 in deposits of Triassic age, and is found again in the Jurassic, 

 Cretaceous, and Oligocene. In the lithographic limestone of 

 Solenhofen in Bavaria, which is of Upper Jurassic age, Limulus is 

 common and is represented by several species. One species is 

 known from the Chalk of Lebanon, and another occurs in 

 the Oligocene of Saxony. No other genus of the Xiphosura 



1 Quart. J. Micr. ,V. xxxi., 1890, p. 379 ; Proc. Cambr. Phil. Soc. ix., 1895-1898, 

 p. 19 ; J. Anal. Physiol. xxxiii., 1899, p. 154. 



2 Quart. J. Micr. Sci. xxxi., 1890, p. 317. 



3 I am indebted to Mr. Henry Woods for these paragraphs oil fossil Xiphosura. 



