x CLASSIFICATION YI FI 
Japan; and (iii.) 7. hoeveni, Pocock (= ZL. MoLUCCANUS, Van 
der Hoeven), found in the Moluccas. 
Genus B. Carcinoscorpius with one species, C. rotundicauda 
(Latreille) (= Z. RorUNDICAUDA, Latreille). It occupies a more 
westerly area than 7’ gigas or than 7. 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 
cills and the absence of Malpighian tubules, both being features 
associated with aquatic life As long ago as 1829 Straus- 
Diireckheim 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,’ 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.” 
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 lmestone 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. Mier. Sci. xxxi., 1890, p. 379; Proc. Cambr. Phil. Soc. ix., 1895-1898, 
p- 19; J. Anat. Physiol. xxxili., 1899, p. 154. 
2 Quart. J. Mier. Sci. xxxi., 1890, p. 317. 
* T am indebted to Mr. Henry Woods for these paragraphs on fossil Xiphosura. 
