Jaxoary 1, 1898.] 



KNOWLEDGE 



3 



common starting point for all the Crustacea must lie 

 indefinitely further back ; and in fact it is not till the pre- 

 Cambrian period that all the branches are made to join 

 the central stem, while of the earlier points of junction 

 between the branches themselves it must be admitted that 



till they melt into an undifferentiated original. Some 

 generalized forms are indeed quoted from the record of 

 the rocks, but they are few and obscure compared with the 

 desires and expectations of the evolutionist. 



In a future cliapter an attempt will be made to show how 



Fig. 4. — Cardisoma r/uanhumi (Latreille). A West Indian Land Crab. 



most are highly oonjectural. The true afiSnities of a modern 

 species are often only discovered by careful dissection, and 

 such a process is rarely possible with mangled remains in 

 an obdurate fossil. Sometimes, when the rock specimens 

 are exceptionally clear, the characters displayed are dis- 

 tressingly like those familiar to us in living forms. Thus, 

 according to Dr. Ortmann, a fossil crawfish from the Upper 



Chalk is more nearly 

 related than any 

 extant species to 

 the modern Linuparis 

 tririonits (De Haan) of 

 Japanese waters. It 

 is imgracious to find 

 fault with nature. 

 Perhaps the re- 

 searches of geology 

 are in fault, or per- 

 haps there are rays, 

 yet waiting to be 

 discovered by the 

 physicist, which will 

 penetrate the secrets 

 of an obliterated past. 

 Properly to attest the 

 work of evolution in 

 nature we sorely need 

 to recover a series of 

 lost pictures. They 

 should be a kind of 

 dissolving views 

 carrying us back to the dawn of life, with the features of 

 all existing forms not abruptly but graduaUy fading away, 



a belief in the unity of the class Crustacea may be founded 

 on the internal evidence of extant species. That this is 

 not, on the face of it, a very simple task, might be inferred 

 from the few illustrations here brought together. They 

 represent a decapod, an isopod, a phyllopod, a parasitic 

 copepod, and a cirripede or cirrhopod, thus ranging from 

 the highest to the lowest ranks of the crustacean common- 

 wealth. Since nature has ordained that the writer of 

 " Hamlet " should have personal identity in common with a 

 speechless babe, a land crab need not be too proud to own 

 a barnacle for its distant cousin. 



Fio. 5. — Glyptonoliis sabini (Kruyer). 

 An Arctic Isopod. 



A DROWNED CONTINENT- 



By K. Lydekkkb, b.a., f.k.s. 



AS many of our readers are doubtless aware, deep 

 boring operations are being undertaken in the 

 island of Funafuti, in the EUice group of 

 Polynesia, with the primary object of ascertaining 

 the depth to which coral rock, or limestone of 

 coral origin, extends. If it were found that such coral- 

 made material extended to depths far below the level at 

 which living coral can exist, there would be evidence that 

 the island on which the experiment was conducted had 

 subsided. And if subsidence were thus proved to have 

 taken place in a single island selected almost at random, 

 the conclusion could hardly be resisted that the greater 

 part, if not the whole, of Polynesia must likewise be a 

 subsiding area, or, in other words, the remnants of a 

 drowned continent, some of the higher lands of which 

 are indicated by the atolls and other islands of the Coral 

 Sea. It is, therefore, a favourable opportunity for a few 



