238 



PALJEONTOLOGY OF NEW-YOKK. 



the two carboniferous genera Palachinus and Arch^EOcidaris. Here are at least some links 

 wanting, or the Cystideae in lower silurian times approached very rapidly to the echinidean 

 character, if the apparent analogies be real ones. On the other hand, we pass from Hcmicosmites 

 to Crypiocrinites, which is a lower silurian genus, through the four succeeding genera, all of 

 which are upper silurian ; and thence through Pentremites, which is both devonian and car- 

 boniferous, to the AsTERiAD^ and Ophiurid.e. However close, therefore, the links may appear 

 from structural affinities, there is a vast space of time between the occurrence of Jigelacrinifes* 

 and the allied carboniferous genera ; and we might justly question the authority of Geology in 

 such a case, if no intermediate types should be found. On the other hand, the links connecting 

 these genera with Asteriad^e are more numerous, and more closely connected in the order of 

 time, and the direction may be true ; still there are a great number of forms yet to be known, 

 which will perhaps modify any view at present given of the affinities of these genera. 



The following species of cystideans have been found in the shale of the Niagara group at 

 Lockport ; and I am indebted to the zeal of Col. E. Jewett of that place, for being able to 

 present figures of well preserved specimensf. They offer very close analogies with those 

 described by Prof. Forbes from Dudley in England ; but one of them, at least, is generically 

 distinct, and the species are all quite dissimilar. 



Genus C ALLOC YSTITES (not), gen.). 

 [Gr. xaXof, pulcher, and xuifris, vesica.^ 



Body ovoid or sub-spheroidal, composed of four series of plates, three of which are con- 

 spicuous, the fourth scarcely exposed ; basal plates four, unequal ; costal plates or second 

 series eight, third series probably of the same number, with a fourth series of small plates 

 forming the apex. Ovarian orifice conspicuous, closed by a pyramid of triangular plates ; 

 pectinated apertures in pairs on three parts of the body ; arms five or more, radiating from 

 the apex and folded back upon the sides, resting in a broad shallow groove and distinctly 

 projecting above the surface, composed of a double series of joints separated by a narrow 

 groove ; articulated fingers attached to the arms in a double row, separated by the groove. 

 Oral orifice below the apex, with an anal pore near it, and a porous tubercle above and a little 

 on one side. Column short, composed of thin joints which diminish rapidly from the body. 



This cystidean, in its general characters and habit, is closely related to Pseudocrinites, and 

 also to ApiocYSTTTEs ; but it will be perceived at once that there are important differences in 

 the structure of the body. It commences with four basal plates, as the genera mentioned ; but 



' This genus is used as defined by Prof. Forbes, and is not the Agelacrinites of Vanuxem. 



t Among the specimens of Caryockinus collected at Lockpoit several yens since, I discovered some specimens 

 of these curious fossils ; but tlicy were so com]>letely coated with pyritous shale, that I was unable to ascertain their 

 structure, till the more fortunate discoveries which have brought to light the beautiful forms illustrated in Plates 50 

 and &1 . 



