Species ok tiik Hamilton Gkoup. 



67 



presei'vation or to adventitious deposits of calcareous matter ujKin projecting 

 points. 



Dimensions. The length of the specimen is 85 mm., but neither l^ase nor 

 aperture is retained. Its width at the upper extremity is 100 mm. 



Locality. In" the Hamilton shales, shore of Canandaigua lake, N. Y. 



ROEMERLSPONGIA, gen. nov. 

 1883. Z>icti/oj)hi/to)i, FGvd. Roemer. Zeitschr. der Deutsch. Geolog. Gesellsch. 

 vol. 35, p. 704, figs, a, b (p. 706). 

 Obconical rapidly expanding cups apparently arising from an acute base. 

 Siirface divided by strong, sube(pial vertical spicular bundles, crossed by nar- 

 rower horizontal bands. The cpiadrules thus fonned are all convex and 

 appear not to be subdivided by subordinate series of spicular bands. Toward 

 the base of the sponge the meshes are less regular than elsewhere. 

 Type, Dictyophytoii (rerolsteinensis, F. Roemer. 



RoEMEKispoNGiA Geuolsteinensis, F. Roeuiei', (sp.). 

 1883. Dictyophytoii Gerolsteinense, F. Roemer, loc. cit. 



In a " Notiz uher die Gattuiuj Dictyophytoii!\ the late Ferdinand Roemer 

 described, as above cited, an interesting Dictyosponge from the middle Devo- 

 nian of the Eifel. This descrip- 

 tion is as follows : "It shows, like 

 the former fossil (Tetraganis 

 [^Prismodictya] Eifeliensis, F. 

 Roemer) a surface divided into 

 rectangular areas, but the sub- 

 division is less regular and more 

 simple. The vertical rods are 

 much stronger than the horizontal 

 rods and, inasmuch as new ones 

 appear toward the aperture, are 

 not quite straight. Moreover the 

 transverse i-ods do not always 

 make right angles with the verti- 



° " nouBE 12. RoemtritponoUi Qtroiaeintntii. (After P. Roemer). The 



Cal rods, but are, especially over conTexlty9fthequadrulesl8notwell8iiown in these copies. 



the l()\\er part, directed obliquely against them. * * * farther sub- 

 division of the rectangular areas by liner spicules is wanting." 



