INYERTEBEATA. 319 



The poly zoary agrees in most of its characters with Ptilodictya, but 

 possesses tabulate cells. The following new species are described and 

 figured : — Ptilodicti/a cosciniformis^ Fenestella Davidso7ii, and Geramo- 

 iwra Huronensis, from the Hamilton formation of Ontario ; and JRete- 

 pora Trentomnsis from the Trenton Limestone of Ontario. H. A. N. 



Nicholson, Prof. H. A. On some of the Massive Porms of Chcetetes 

 from the Lower Silurian. Geol. Mag. dec. ii. vol. ii. pp. 175-177. 



Discusses the affinities of Chcetetes petroi^olitanus^ Pand., and some 

 allied forms. The name of G. undidatus is provisionally suggested for 

 the lobate and undulated masses included by American palaeontologists 

 under G. lyco])erdon^ Say. H. A. N. 



. Descriptions of Species of Hippotlioa and Alecto from the 



Lower Silurian Eocks of Ohio, with a description of Aidopora 

 arachnoidea, HaU. Ann. Nat. Hist. ser. 4, vol. xv. pp. 123-127, 

 pi. xi. 

 Describes and figures as new species, Alecto aidoporoides^ A. frondosat 

 and A. confasa, from the Cincinnati Group of Ohio. Gives a full de- 

 scription of Alecto injlata and Aidopora aracJinoidea, and shows that 

 the former is properly referable to the genus Hippotlioa. H. A. N. 



Descriptions of New Species of Polyzoa from the Lower and 



Upper Silurian liocks of North America. Ann. Nat. Hist, ser* 4, 

 voL XV. pp. 177-183, pi. xiv. 

 The following species of Polyzoa are described as new, from the 

 Cincinnati Group (L. Silurian) of Ohio : — Ptilodictya falciformis, P. 

 emacefata^ P. fiagellmn^ P. fenestelliformis, P. (?) arctipora, and Gera- 

 mopora Ohioensis. The name of Fenestella nervata is given to a new 

 species from the Guelph Limestones (U. Silurian) of Cedarville, Ohio. 



H. A. N. 



On a new Genus and some new Species of Graptolites from 



the Skiddaw Slates. An7i. Nat. Hist. ser. 4, vol. xvi. pp. 269- 



273, pi. vii. 

 The new genus Azygograptus is founded for Graptolites in which 

 the polypary is simple, unilateral, consisting of a single monoprionidian 

 stipe, which is developed from the central portion of the sicula on one 

 side. The only species known is named A. Lapwortlii. The new 

 species Thkmnograptus Doveri and Didymograptus gihheridus are 

 described. H. A. N. 



On the Mode of Growth and Increase amongst the Corals of 



the Palaeozoic Period. Trans. B. Soc. Edin. vol. xxvii. pp. 237- 



249, pi. xvii. 

 Treats of the general and special peculiarities of growth and non- 

 sexual reproduction exhibited by the Palaeozoic corals. The general 

 modes of growth are distinguished into : — 1. Simple calicular gemmation ; 

 2. Compound calicular gemmation ; 3. Basal gemmation ; 4. Parietal 

 gemmation ; and 5. Pission. The rest of the paper is a consideration 



