150 MATTHEW ON CAMBEIAN 



HYALOSTELIA, Zittel. 

 Hyalostelia minima, n. sp. (PI. VII, fig. 10.) 



A tuft of spiciilos. Elongate, ascending, branched, consisting of groups of cemented 

 spicules, ending iu pointed or recurved extremities, or a loose open mass of aggregated 

 spicules. Having root-like branches at the foot of the tuft of spicules. 



This appears to be an anchoring group of spicules which terminated upward in the 

 body of the sponge. 



Size. — Length, 4 mm. ; width at the branches, IJ mm. 



Horizon and Locality. — Red shales of Div. 1 of the Basal series at Caton's Island, 

 Greenwich, N.B. 



IV.— CRIIVOIDEA. 



PLATYSOLENITES, Pander. 

 Platysolenites antiquissimus, Eichw. Sp. (PI. VII, figs. 11 a-c.) 



18.51. Plalysokniteg, Pander iu Bull, Soc. Geol. de France, 2 sér., vol. 8, p. 253. 



1858. " Ehrenberg in Monatsbericht, Bert, Akad, p. 329, 336. 



I860. '' anliquimmxi,% Eichw., Letb. ross. auc. per p. 678, T. 33, F. 19. 



1881. " F. Schmidt, Revision der ostbalti.«chen siUirichen Trilbiten, abtheil. I, p. 13, F. 1. 



1888. " " Mem. Acad. Imp. des Sci. St. Petersburg, VII., XXXVL, No. 2, p. 26. 



F. Schimdt, in the last named publication, gives a full description of this " Encrinite 

 stalk," and of the opinions of several naturalists who have examined it. Being the oldest 

 fossils known iu the Lower Cambrian beds of Russia, they have attracted much attention 

 Pander, who first described these " minute, hard, flattened little reeds," could not decide 

 upon their place in the system of nature. Ehrenberg, who studied them microscopically, 

 could find no structure in their hard shells, and was inclined to regard them as similar to 

 the mineral crust that encloses the stems of certain Algœ. Eichwald referred them to the 

 Annelids, considering their hard calcareous shells to be similar to those of Serpuhe. F. 

 Schmidt says that he was brought to consider them parts of Cystidians, because of their 

 articulated appearance. He also states that iu 1870 Giimbel could find iu them nothing 

 but " criuoid stalks." They have been found by Mickwitz in abundance on the sea shore, 

 near Reval and Kostifer on the Baltic, where they have been washed out of the Cambrian 

 " Blue Clay." Herr Schmidt describes those from the lower Glauconite sand (in the Blue 

 clay) as " somewhat flatly compressed little reeds with transverse divisions and joints, 

 about 2 mm. broad and 15 mm. long. The thickness of the shell about \ mm., and the 

 length of the joints about | mm. The structure of tfee shell is plainly crystallo-calcareous 

 as with other criuoid stalks." 



In the examples from Caton's Island the crystalline structure of the shell is preserved, 

 and the interior is occupied by a black mass which appears to be the carbonized contents 

 of the cavity. The fossil is inclined to split readily along the middle, where the two sets 

 of plates meet, and here the edges of the plates are rounded, where probably there was a 

 connecting cartilage. On referring to F. Schmidt's figures of the Russian examples of 

 this species," it will be seen that the half of the stem, or arm is often thus preserved. 



' IhiJ. PI. ii. 33 a and /-. 



