Intkoductorv. Sf) 



The presence of inura,! (Openings in these nienihers of the I'i.kctosi'onoid/B, 

 is a feature of similarity with Euplectklla and its allies (Eiii'lectklmd^:), 

 but in none of the Dictyospongid^ is there evidence of precisely similar 

 structures. The Dictyospongid^e are distinguished from all of these earlier 

 hexactinellids by the presence of an inner wall, composed of strong vertical 

 and horizontal fascicles of rods reticulating at right angles. In the great 

 majority of instances these reticulating bundles are present in a gradational 

 series, the size of the bundle depending upon the number of rods it contains, 

 rather than upon the size of these rods. In normal forms the series (^f 

 bundles and, consequently, the series of quadrules made by them, numbei-s as 

 high as five or even six, the finer reticidation of the sixth series being observ- 

 able only in instances of the most favorable preservation. There are some 

 genera, however, included within the limits of this family, in which thei-e 

 exists but a single set of reticulating bundles. Thus in Piiysospongia, there 



oeacribed l)y Dawson as J'rotosponyia delicatula, from the Little Metis slates. In tlie very extensive 

 material representing the Utica slate sponges which has been under examination in the preparation of this 

 volume, similar obscnre bodies have frequently been seen. There are however, associated with them, 

 othei spherical sponges, showing very distinctly the composition of the skeleton and presenting some 

 highly interesting characters. These bodies in their adult condition and as usually preserved, appear as 

 illustrated in figure 18 (Plate I), that is to say, they are circular disks undoubtedly representing orgiually 

 spherical sponges under compression. In no instance bus any trace of aperture been obscrvjd. These 

 bodies are so broken by the parting of the shaly laminae that almost invariably a portion of the outer wall 

 oi the sphere adheres to one side of the matrix, so that ligure 18, which represents the usual condition of 

 the fossil, shows, over the circular central portion, the inner wall of the sponge, the j)cripheral ring being 

 the thickness of the cup to the outer wall. A good exposure of the outer surface is very rarely seen. The 

 inner surface of the sponge bears a great number of clearly delined areoles or mural openings, which are 

 much more closely arranged than in Cj/athodicli/a reticulata, and the network by which they are surrounded 

 is highly irregular, devoid of quadrate meshes, though clearly made np of simple stauractine spicules which 

 are involved in not fully resolvable patches of i>yriie (see figures 19 and 20). The thickness of the wall as 

 shown in figures 18 and 22 is considerable, the structure being composeil of short rod-like 8[iieules which 

 may all be stauractine and the entering arm of the dermal peiitactins, but the specimens do not show this 

 conclusively. An entire layer is formed of a single thin lamina of stauractine spicules making a regular 

 quadrate mesh in which the horizontal rays of the spicules may slightly overlap, but no distinct spiculnr 

 bundles are formed and no filiform rods are present. A portion of this outer layer is shown in 

 figure 20, traces of the mural openings being seen on the matrix beneath it. The entire outer surface is 

 armed with short, erect spicules. Bodies of this character occur in clusters. One slab measuring 18x8 

 inches bears twenty seven of them, all of normal size. 



The same rock iilso contains clusters of much smaller circular bodies varying somewhat in size, 

 as shown iu figure IG. These also seldom show evidence of an aperture except sueh as is seen in one of the 

 larger examples in figure 14, and this appearance may be wholly due to the exfoliation of a fragment of 

 the slate. The substance of the smaller of these spherical bodies or disks is an unresolvable massofpyrite, 

 of similar character to that described by Uaui'K for Teganium aubsphcericum, except that about the periph- 

 ery are erect spicules of proportionally much greater length than the surface spicules in the large spheres 

 just described (figure 17). With slight increase in size, however, the spicular skeleton with its mural 

 areoles becomes grailually defined, leading to the conclusion that these Teganium-WkB bodies are young of 

 the larger forms. There is still doubt as to the relation of all of these forms to the Cyathophyciia auhspha;- 

 ricus of Walcott and the Teganium aiibsphwricum of RAtTFF." There is little iu their structure to suggest 

 the characters of that species given in the analysis by either of these writers, save the spherical form ascribed 

 to it by the former and the obscure spiculization recorded by the latter, notable only in the very young of 

 our specimens. 



The generic characters ascribed to Teganium fail to apply to these spheroidal sponges, save in part to 

 their youngest stages, and while we can not be certain that Dr. Kaufk may not have had similar bodies 

 before him in the description of Teganium, the uncertainty attending the description and illustration given 



