460 Scien tific In telligence. 



eurypterids, and lacks the two movable claws. This simple form 

 of the walking leg is also exhibited in a very remarkable manner 

 by the Siluric Palseophonus. It is quite safe to infer that this is 

 the form of the cephalothoracic appendages inherited from the 

 common ancestor. 



" A corollary of these inferences is that neither Limulus nor 

 the scorpions is derivable from the eurypterids, but that all three, 

 while related, have early separated ; and that the eurypterids are 

 still nearest in their general aspect to this common ancestor. . . . 

 There is no reason to doubt that, as there are eurypterids in the 

 Cambric, the scorpions also reach back to that era and the diver- 

 sion from the common ancestor must have already been inau- 

 gurated in early Cambric time" (146-7). 



" As the most primitive and earliest crustaceans, the trilobites, 

 are clearly not ancestrally or otherwise closely related to the 

 eurypterids and the latter even in the Cambric are far removed 

 from any possible synthetic ancestors, it is a fair question whether 

 it is not proper to look for more primitive arthropods than the 

 crustaceans as ancestors of the eurypterids. . . . Bernard derives 

 the Crustacea from a bent carnivorous annelid, a view which 

 Beecher regards as partly verified by his discoveries concerning 

 the ventral anatomy of the trilobites, and it is therefore worthy 

 of consideration in this place. If we consider the absence of any- 

 thing in the ontogeny of the eurypterids that would suggest a 

 crustacean nauplius stage, the admitted absence of all crustacean 

 features in the adult forms, and the equal absence of all crustacean 

 features in the ontogenies of Limulus and the scorpion, it becomes 

 manifest that the inference of the derivation of these classes from 

 arthropods more primitive than the Crustaceans, seems well 

 founded" (148-9). c. s. 



2. Correlation of the Devonian system, of the Hock Island 

 region ; by W. Elmer Ekblaw. Trans. 111. Acad. Sci., 5th 

 Ann. Meeting, Feb. 23, 24, 1912, 15 pp., 2 figs.— An excellent 

 short paper listing according to the individual beds 109 species of 

 the higher Middle Devonian as exposed in Rock Island and 

 Henry counties, Illinois. This fauna is clearly of the Dakotan 

 province, as 83 per cent of the determined forms are common to 

 these two western areas. c. s. 



3. Unterrneerische Gleitung bei Trenton Falls (Xord-Amer- 

 ikaj und ihr Verhdltnis zu dhnlichen Storungsbildern / by 

 F. Felix Hahn. Neues Jahrb. fur Min., Geol. u. Pal., Beilage- 

 Bd. xxxvi, pp. 1-41, pis. I— III, 1912. — A valuable paper explain- 

 ing local crumpled beds, edgewise conglomerates, and in part 

 intraformational conglomerates, as due in the main to slipping of 

 the deposits, while still soft or but little consolidated, on slight 

 inclines of the sea bottom. Many examples are given in forma- 

 tions throughout the geologic column. This interpretation has a 

 direct bearing on the significance of discontinuities. c. s. 



4. Iowa Geological Survey ; Vol. XXI, Annual Reports, 

 1910 and 1911, with accompanying papers, prepared in coopera- 



