gg DlCTYOSPONGID^E. 



distinct and simple bodies. Their association with the cruciform spicules 

 is so close and invariable as to enhance the probability of the organic 

 connection of the two, and yet we do not know a similar structure among the 

 hexactinellids. It has been impossible to gain a conception of the original 

 form of the sponges to which these masses of spicules belong. The generic 

 reference now made of the species is, therefore, quite uncertain. 



Locality. In the Marcellus shales of the Hamilton group, Livonia, N. Y. 



CLATHROSPONGIA, Hall. 

 (For description see page 121.) 



Cl^throspongia (?) Hamiltonensis, Hall (sp.). 



Plate xiv, Fig. 1. 



1884. Dictijophyton Hamiltomnse, Hall. Thirty-fifth Ann. Kept. N. Y. State 

 Museum Natural History, p. 468. 



Sponge broadly cyathif orm, regularly and rapidly expanding from the base. 

 Surface apparently regularly obconical, though a sub-prismatic appearance is 

 given to it by the very strong longitudinal spicular bands. 



Reticulum characterized by the sharply elevated bands of the first order 

 which produce large quadrules. Near the middle of the cup these primary 

 meshes measure about 12 mm. on each side, but become smaller toward the base 

 of the spOnge where the primary bands seem to have been more or less free, but 

 it is not clear whether these were developed into bundles of anchoring spicules 

 independent of the reticulum. The intersections of the primaiy spicular bands 

 are thickened and distinctly nodate. A second and third series of bands are 

 more or less clearly defined, and the interspaces are very closely reticulated. 



The preservation of the single known specimen of this species is peculiar 

 and unique. The entire reticulum is compactly calcified, lying in an argil- 

 laceous shale. This calcareous matter seems to have been deposited over the 

 inner surface of the net-work or to have replaced it from within, as traces of 

 the finest spicular lines may be seen over the surfaces of the coarsest bands ; 

 this would indicate the posterior position of the finer net-work to the primary 

 longitudinal and transverse bands. The elevation and prominence of the 

 latter convey the impression that in their original condition they were extended 

 into vertical tufts of similar character to the mural lamellae in the typical 

 Chemxmg forms of Clathrospongia ; the species is therefore referred to this 

 genus until it shall have become more fully known. The lesser spicular bands 

 abound in irregular nodose swellings which may be partially due to imperfect 



