Species op the Chemung Group. 101 



connection therewith other nodose species from the same formation, most 

 kindly submitted by Professor Barrois. 



Dimensions. The material stndied shows wide differences in respect to 

 size. Some comparatively small individuals indicate full growth, while occa- 

 sionally much larger specimens evince immaturity in the development of the 

 nodes. The specimen figured on Plate v (tig. 4), is a very good example 

 of an average individual, its onginal length having been about 200 mm. A 

 large but slender cup has a length of 280 mm., Avith a greatest diameter 

 of 95 mm., while a shorter example, 220 ram. in length, has a maximum 

 width of 135 mm. 



Localities. In the lower and middle portions of the Chemung sand- 

 stones; in the town of Italy, Yates county, and in the southern part of 

 Naples, Ontario county; at various localities in Steuben county principally 

 west of the Cohocton river. Brown hill school-house. Potter hill, scattered 

 localities in the towns of Howard and Avoca. The species also occurs, 

 though rarely, in the Jenks quarry at Bath. 



Hydnocebas tuberosum, Conrad, 

 var. GLOS8EMA, var. nov. 



Plate vii, Figs. 4, 5 ; Plate ix, Fia. 2. 



This name is introduced for a form distinguished from IT. tuheros^im by 

 its slender, very gradually expanding cup, with low, horizontal constric- 

 tions and depressed, subacute nodes in five or six well-developed rows. 

 The vaiiety is based upon several specimens whose dissimilarity from forms 

 of IL tuberosum' is very apparent. In both of the specimens figured the 

 spicular net work is finer, that is the principal quadrules are smaller than 

 in II. taberosuni. The specimen on Plate ix, fig. 2, is interesting for the traces it 

 shows of annelidan tubes, suggesting a coramens;ilism, similar evidences of 

 which have been observed in other Dictyosponges. (See page 81, and also 

 remarks on Symbiosis in the Hexactinellida, page 21.) 



Locality. In the sandstones of the Chemung group, in New York. 

 Both examples are from unknown localities, but probably from the middle 

 portion of the group in northern Steuben county. 



Hydnoceras Bathense, sp. nov. 



Plate hi, Fig. 3; Plate viii, Fig. 4; Plate ix, Fig. 1. 



This species has the same general form of cup as Hydnoceras tuherosxim, 

 but is distinguished from that by the greater number of horizontal roAvs of 



