112 DlCTYOSPONGID^. 



"This species maybe a form of D. tuherosum, Hall, 1. c, p. 90, pi. iii, fig. 1, 

 which has the articulations inflated into short, obtuse tubercles, some of 

 them broken, but none prolonged as branches. The specimens I have had for 

 examination represent the tubercles arranged in horizontal rows, as in D. 

 tuheromirn, but instead of being round and obtuse they are prolonged horizon- 

 tally into short branches inflated into half round knots at the apex. The 

 ribbon-like divisions surrounding the stems and branches are parallel and 

 quite distinct. 



" Habitat. Upper Chemung, head of Hill creek, Charleston township, 

 Tioga county, Penna. A. Sherwood." 



The foregoing description, based upon a conception of the vegetable 

 nature of this organism, was derived from highly impei-fect specimens. It 

 might in fact, be difficult to recognize, in the absence of illustrations, the form 

 which it is intended to portray, were it not that we have specimens collected 

 from the same locality by Mr. Andrew Sherwood, and that these represent the 

 only nodose Dictyosponge known to occur there. The fossil has proven to 

 be a remarkable and extremely interesting one, and by careful nianipulation 

 of the very badly collected material representing it, it has been possible to 

 elucidate the main features of its structure. 



Sponge, in general form, stout and subturbinate, resting upon along, sub- 

 cylindrical, hollow base or pedicel. The latter expands very gradually, is sub- 

 circular in cross-section and smooth on the exterior. Toward its upper portion 

 it broadens where passing into or joining the vase-like upper part of the 

 sponge. Its length seems to be variable, irrespective of variations in the size 

 of the nodiferous vase ; ^vhere best preserved it is considerably longer than 

 the vase, and even here its basal point is not retained. In this instance its 

 width is about one-fifth that of the body of the vase, and this varies but little 

 from top to bottom except at the proximal expansion. 



Form and general aspect of the upper part or vase as in IIydnoceras. 

 Body of the vase subcylindrical, somewhat rapidly expanding beneath, and 

 slightly contracting at or near the aperture. Surface covered with a series of 

 compound iz-regular, pendulous lobes or pouches which are arranged in eight 

 vertical and four horizontal rows, these being separated by low vertical 

 depressions and deeper horizontal constrictions. The specimens are so pre- 

 served that most of these nodes are greatly flattened and somewhat distorted 

 from their noi-mal shape, though those lying in the plane of lamination of the 

 rock have generally escaped such distortion. The structure of these compound 

 nodes is essentially as follows : Of the three lower horizontal rows, each rises 



