Eevieus — Nichohon and Lydekker's Paleontology. 87 



primary orders of Regulares and Irregulares, proposed by Etheridge 

 and Carpenter, are adopted. The long extinct Cystideans present 

 considerable difficulties in their arrangement. ]n the Appendix, Dr. 

 Carpenter contributes a note on certain structural points of some of 

 the Bohemian forms described in Barrande's posthumous work on 

 this group. 



In the chapter on fossil Annelids, the microscopic structure of 

 some of the Tubicolas is figured, as well as that of the peculiar 

 Cornulites from the Wenlock. Some of the minute chitinous jaws 

 of the Ordovician Polychetge are also shown. 



Barrande's classification of the Trilobites is adhered to, but it 

 seems that even in this group no strict zoological arrangement is as 

 yet possible ; it is regarded as more nearly related to the Merostomata 

 than to any other division of the Crustacea. Figures are given of 

 the minute structure of the test, and also of the appendages discovered 

 by Walcott on the under-surface of the body of Asaphns. 



Under the Arachnida, interesting figures are given of the structure 

 of the chitinous skin of a fossil Scorpion from the Carboniferous 

 rocks of Scotland, and of a recent specimen of this group. 



Several new figures of the minute structure of the Polyzoa and 

 of the beautifully-marked cells of the Cheilostomata are added in 

 this edition. The peculiar form of the cell-apertures in Coscinium 

 cribriforme (p. 610), and in Cystodictya Gilberti (p. 631) is very 

 suspiciously like those of the Monticuliporoid Fistulipora trifoliata 

 (p. 358), and might lead one to suppose a near relationship between 

 these forms. 



Owing to the comprehensive labours of the late Dr. Davidson, 

 there are fewer changes in the Brachiopoda than in other groups. 

 The principal novelties are the forms from the Carboniferous strata 

 of India, described by Waagen under the names of Oldhamina and 

 Lyttonia. 



In the Lamellibranchiata, Fischer's new classification is adopted 

 in preference to the former one based on the presence or absence of 

 siphons. As becomes the importance of this group, most of the 

 representative types are figured. 



The old divisions of the Gasteropoda into the Pulmonata and 

 Branchiata are maintained, but the Chitons and Dentaliidse are 

 regarded as forming two separate classes of Mollusca. In the Ptero- 

 poda, the delicate calcareous tubes known as Stijliola fissurella are 

 believed to be genuine representatives of the group. Some of the 

 Devonian Limestones in North America are almost exclusively com- 

 posed of these small tubes ; the section figured shows this remark- 

 ably well. Tentaculites is still retained in the Pteropoda, but the 

 structure of its shell throws considerable doubt on its relationship 

 to this group. 



The concluding four chapters of this volume ti-eat of the Cepha- 

 lopoda. Many additional figures illustrate their structure and early 

 stages of growth. In the Nautiloidea the family divisions lately 

 proposed by Foord are adopted, and the Ammonites are arranged 

 according to the classification of von Zittel. 



(To be continued.) 



