444 Scientific Intelligence. 



with the warm water coral fauna represented by that of the 

 Onondaga formation ; this the reviewer holds is an invasion 

 from the Gulf region through the Indiana Basin, thence spreading 

 eastward into New York while one (Machmracanthus sulcatus) 

 continues as far as Gaspe, Quebec. A further analysis of the 

 American species shows that of this warm water fauna at least 

 three genera (Ptyctodas, Acantholepis, and Dinichthys) spread 

 westward into the Dakota sea while the western province furnished 

 but one migrant (Heter acanthus), into the Mississippian area. 



Under Geological Conclusions, in regard to the paths of migra- 

 tion as worked out by Schuchert and Clarke, the author remarks 

 that "the known distribution of the fishes is in all respects con- 

 sonant with, and one is tempted to add, confirmatory of the prin- 

 ciples that have been formulated from a study of the invertebrates." 

 The American Middle Devonian fish assemblage of the Appa- 

 lachian basin is found to occur somewhat earlier in Bohemia, 

 migrating westward across the Atlantic (probably not northwest- 

 ward as stated by the author) and into the Mississippian sea by 

 way of the Indiana basin. "The most conspicuous elements of 

 the fauna are Arthrodires and Ptyctodonts, groups which began 

 immediately upon their introduction to attain a most remarkable 

 development. Throughout the Hamilton, and later Devonic, con- 

 ditions must have been eminently favorable in the Appalachian 

 sea for the furthur specialization of armor-clad Dipnoans of the 

 type represented by Dinichthys and its congeners. Like their 

 earliest predecessors, thev became of greatest importance locally 

 in Ohio." 



Of the Agnatha, or fish-like vertebrates, the author does not at 

 all follow the suggestion of Professor Patten that these animals 

 were developed out of some Arthropod stock. He holds the class 

 to be an independent one, differing from the true fishes in not 

 having "the slightest trace of ordinary jaws, of a segmented axial 

 skeleton in the trunk, or of arches for the support of paired limbs. 

 Indeed, appendages themselves are confined to a single order, the 

 Antiarcha, where oarlike swimming organs appear to have devel- 

 oped from an integumentary fold on either side of the body, 

 unsupported by rays, and in a manner fundamentally different 

 from the fins of the typical fishes." That they are not transitional 

 between vertebrates and invertebrates (either Ascidia, Crustacea 

 or Arachnida) the author holds is disproved as follows: (1) the 

 dermal plates are composed of true bone ; (2) the head shield and 

 body armor of Asterolepids have a well developed sensory canal 

 system; (3) in Pterichthys, at least, there is a tail covered with 

 scales, a dorsal tin, and a genuinely piscine heterocercal caudal fin." 



The oldest fish remains so far discovered (Ordovician of Colo- 

 rado) and made known by Walcott, the author is not called upon 

 to treat but admits one of the three species, Astraspis desiderata, 

 to the Agnatha. 



The Dipneusti or lung-fishes are treated in considerable detail. 

 There are a lame number of them in the American Devonian 



