458 Scientific Intelligence. 



II. Geology and Mineralogy. 



1. The Eurypterida of New York; by John M. Clarke and 

 Rudolf Ruedemann. New York State Mus., Mem. 14, 2 vols., 

 638 pp., 88 pis., 121 text figs., 1912. — This monograph on the 

 Eurypterida of America — for it treats of all American forms — is 

 truly a monumental work and a model for all paleontologists to 

 follow, provided they have a liberal state treasury back of them. 

 In this work one can study Eurypterida from any viewpoint per- 

 mitted paleontologists. Here we may find their chronology, their 

 development from baby stages prophetic of unknown ancestors to 

 adults, and their relations to scorpions, horse-shoe crabs, trilobites, 

 and even to the hypothetic annelids. The volume of plates is 

 not only a storehouse of merostome information but as well a 

 work of art. In it the text-book writer will find the animals pic- 

 tured true to life and easy of incorporation as text figures. 



An adequate summary of the results obtained cannot be given 

 here, but only a few of the striking ones picked out here and 

 there. The oldest reported merostomes are those of late Protero- 

 zoic time (Belt formation), known as Beltina danai Walcott. 

 Regarding them the authors state : " We entertain no doubt that 

 these bodies, or the greater part, are of organic origin and while 

 unable, after careful study, to convince ourselves that they are 

 merostomatous, yet to renewed efforts in the field they do give 

 promise of a recognizable fauna" (386). Regarding the remark- 

 able Middle Cambrian forms they write : " It seems to us proba- 

 ble that the Limulava as described are not eurypterids, but 

 constitute a primitive order, though exhibiting some remarkable 

 adaptive features. This order possibly belongs to the Merosto- 

 mata but it is distinctly allied to the crustaceans in such important 

 characters as the structure of the legs and telson, and is therefore 

 much generalized" (410). 



Much has been written about the habitat of these animals, and 

 as Clarke and Ruedemann have seen more material than any 

 other paleontologists their opinion has added value. They say : 



"Summarizing these data we conclude that the eurypterids 

 lived in the sea from Cambric to Siluric time. They had then 

 become less sensitive to changes, positive and negative, in the 

 salinity of the water. In fact they seem to have thrived best 

 under conditions of life that exclude most other marine groups of 

 animals, that is, in the marginal, more or less inclosed marine 

 lagoons, accompanied by estuaries receiving delta-forming terres- 

 trial drainage, with prevailing arid or subarid climate, the waters 

 being in some places more than normally briny, in others having 

 less than normal salinity. In other words they were euryhaline 

 or able to live in both salt and brackish water. . . . Thus while 

 the earlier eurypterids were marine and their climacteric fauna 

 euryhaline ; their later habit throughout the Devonic and Car- 

 bonic led them finally into the fresh water " (112). 



