Species of the CiiEHnNG Ghoitp. 107 



broad depressions. AVhen there are but three rows of these nodes, the first 

 or lowest is sharply developed, and at times there is evidence of an obscure 

 row in the apertural region, as shown in one of the specimens figured. When 

 the four rows are nonnally developed those of the first row ai-e small and 

 incipient. The aperture is situated at somewhat less than the usual interval 

 al)ove the last row of nodes, and is expanded to nearly the full diameter of 

 the cup at the last row. The number of nodes in each row, while normally 

 eight, is sometimes but seven on the earliest rows. 



The reticulam is fine, usually sharply retained, and shows primary 

 sjjicular bands midway between the nodes both longitudinally and horizon- 

 tally. The tufted extremities of the nodes are seldom preserved in the speci- 

 mens examined. 



Dimensions. Nearly all the examples of this diminutive and graceful 

 species are entire, a most unusual occurrence among species of this 

 genus. One such individual, mature in all its characters, has a length of 

 40 mm., a width at the first nodes of 8 mm., greatest width of 13 mm. and an 

 apertural diameter of 12 mm. A somewhat stouter specimen has the same 

 length but a maximum diameter of 20 mm. Individuals much smaller than 

 either of these hav'e also been observed. 



Locality. In the sandstones of the lower part of the Chemung group. 

 Nearly fifty individuals, characterized by their slender form and persistently 

 small size, have been found by D. D. Lutiikk, in a single loose slab, in 

 Segur's gully, township of Italy, Yates county, N. Y. Specimens of Hydiw- 

 cei-as tuhei-osum occur in the same rock. 



Hydnoceras bhopalum, sp. nov. 



Plate xxxvii, Figs. 1, 2. 



This form, found only in the Brown hill colony of H. tuberosum, is 

 too unlike the latter to justify its being regai-ded as an abnormal individual 

 expression of that species. 



The sponge is elongate and slender, its most expanded portion at two-thirds 

 of its length from the base, having about thrice the Avidth of the fractured 

 lo^ver end. Nearly the entire lower half of the cup is devoid of well developed 

 nodes, though showing distinctly, under compression, the pnsm-faces. 



The number of horizontal rows of nodes is large, but the nodes them- 

 selves are seldom conspicuously developed. These rows, counting all which 

 show incipient nodes, are eight or nine in number, and appear to bear normally 

 ei'^ht in each row, but in several instances they are irregular in this respect, 



o 



