Spkcips of tfik Ciikmuno Gkoup. 121 



distorted. Some, which became detached or hiy more nearly parallel to the 

 lines of deposition, are better preserved, though in none of the examples is 

 the entire form retained. 



These sponges vary considerably in form and size, the young individuals 

 being slender with broad or narrow annulations at une([ual distances. The 

 largei- individuals have the annulations more regular and equidistant. All 

 the annulations are, as a rule, low and rounded, with broad and shallow inter- 

 spaces. In a specimen measuring 57 mm. in length and having a width at the 

 upper end of 24 mm., there are six annulations at subequal intervals ; a young 

 example 46 mm. long, with a width at the top of 12 mm., and at the bottom 

 of 7 mm., has six annulations at somewhat irregular intervals. The largest frag- 

 ment observed has a diameter of 40 mm. The reticulum in all of these 

 specimens is fine and shows no predominant spicular striae, the prevailing 

 mesh being uniformly from .5 to 1 mm. square. The species is distinctly 

 unlike any of the other forms referred to this genus and although having an 

 aspect somewhat similar to that of O. zonata, diifei's from this in its less regular 

 and unflattened annulations as well as in the character of its reticulation. 



LocaUtij. In the upper part of the Chemung group at Ischua, Cattarau- 

 gus county, N. Y. About fifty individuals were found in place distributed over 

 a very limited area. 



CLATHROSPONGIA, Hall. 



1863. Dwtyophyton, Hall. Sixteenth Ann. Kept. N. Y. State Cab. Nat. 



Hist., p. 90. 

 1882. Clailirospongia, Hall. Notes on the Family Dictyospongidse, Expl. 



pi. 18, figs. 3-4. 

 1884. Dictyophyton {Clatliro&pongia) , Hall. Thirty-fifth Ann. Kept. N. Y. 



State Mus. Nat. Hist., pp. 468-470,474. 

 1890. Dictyophyton, Hall. Ninth Ann. Eept. N. Y. State Geol., pp. 57, 58. 

 This term was introduced without definition and was intended to cover, 

 in a subgeneric sense, the species Dictyophyton abomis^ Hall, which presents a 

 strong development of the erect reticulating surface lamellae such as also 

 occur in the genus Tiiysanodictya. Unlike the species of the latter genus, 

 however, the form of the cup is regularly obconical, and it appears to terminate 

 below in an acute point. There is still some uncertainty in regard to this 

 character, but nevertheless the differences in the form of the cups, and the 

 characters of their earlier growth are evident. It has been found necessary in 

 the consideration of a number of different species where imperfect preserva- 

 tion has precluded definite knowledge of the basal structure, to refer to this 



