BRYOZOA. 679 



< )\rr the basal portion of the zoarium the false outer fene- 

 strules are closed, and the entire space within apparently filled 

 with vesicular tissue. 



This species is closely allied to Fenestella ambigua Hall, from 

 the Niagara shales of Indiana and New York. Its proportions, 

 however, are somewhat smaller, there being only 10 fenestrules 

 and 10 to 18 branches in 1 cm. in the American species. In the 

 latter the outer or false fenestrules are also less regular. 



The propriety of placing species of this kind with Isotrypa is 

 questionable. If the presence of pores on the reverse side of 

 the dissepiments is essential, and we are inclined to admin the 

 point, then they must b:? placed elsewhere. Originally we in- 

 tended to refer the two species to Loculipora, but since seeing 

 figures of the types of that genus we have concluded that they 

 cannot properly go there. Unitrypa, also, was suggested, but 

 we believe that that name should be restricted to forms having 

 the scalre more numerous than the dissepiments. Hall's recently 

 proposed Tectulipora (41st Ann. Kept. X. Y. St. Mus., 1888), 

 is p-obably nearer the mark than any of those mentioned. The 

 description, however, fails to fit the two species in one point, 

 and that is in the statement that the carina? continue over the 

 dissepiments, thus leaving only perforations through the fronds 

 and no median longitudinal channels. These exist not only in 

 the Gotland species, but also in the Niagara and a Hamilton 

 species from Michigan. As the point is one that is not easily 

 determined, it is possible that the objectionable statement is 

 founded upon faulty observation. Until more is known of the 

 type of Tectulipora. and its character fully illustrated, we must 

 be content with referring to the fossils under consideration as 

 above. 



Position and locality: Upper Silurian, Island of Gotland. 



We are indebted to Prof. Gustav Lindstrom for the oppor- 

 tunity of describing this interesting species. The type is in the 

 author's collection. 



About the time the text of this volume had been put into 

 type (Dec. 1st, 1889), Mr. S. A. Miller's valuable work on 

 ''North American Geology and Palaeontology'' appeared. A list 

 of the new genera and species described in this volume had 

 previously been transmitted to him, together with a revised 



