300 PROCEEDINGS OF THE ACADEMY OF [1879. 



1868. (?) Dendrocr. Oswegoensis Meek & Worth. Geol. Rep. III., vol. iii. pi. 



4, fig. 4. (The specimen is too imperfect for identification ) Hudson River 



Gr. Oswego, 111. 

 *1867. Dendrocr. polydactylus Shumand. (Homocrinus polydactylus ) Trnns. 



Acad. Sci. St. Louis, vol. i. p. 78, pi. 1, fig. 6; also Geol Surv. Ohio Pal., 



vol. i. p. 22, pi. 3, fig. 9. Hudson River Gr. Richmond, Ind. 

 *1872. Dendrocr. posticus Hall (Poteriocr. posticus.) 24th Rep. N. Y. St. 



Cab. Nat. Hist., p. 209, pi. 5, figs. 5 and 6. Poteriocr. {Dendrocr.) posticus. 



Meek. Geol. Surv. Ohio, Pal., vol. i. p. 22, pi. 3, figs. 4 a, b, c. Hudson 



Riv. Gr. Cincinnati, 0. 

 1856. Dendrocr. probosciadiatus Billings Geol. Surv. Can., p. 267 ; also Dec. iv. 



p. 38, pi. 3, figs. 3 a-c. Trenton limest. Montreal, Can. 

 1856. Dendrocr. rusticus Billings. Geol. Surv. Can., p. 270 ; also Dec. iv. p. 41, 



pi. 3, figs. 7 a, b. Trenton limest. Ottawa, Can. 

 1856. Dendrocr. similis Billings. Geol. Surv. Can., p. 267; also Dec. iv. p. 40. 



Trenton limest. Ottawa, Canada. 

 1866. Dendrocr. tener Billings. Catalogue Foss. of Anticosti Hudson Riv. Gr. 



Anticosti. Miller's Cat. (We have no means of comparison.) 



B. Subgenus HOMOCRINUS Hall. 

 (Diagram PI. 15, Fig. 6.) 



1852. Geol. Rep. N. Y., vol. ii. p. 185. 



The following is Hall's generic description of Homocrinus: " Crin- 

 oidea having the calyces composed of three series of simple plates, 

 each series consisting of five plates, sometimes one or more irreg- 

 ular plates intercalated between the scapular or third series of 

 plates on one side ; arms proceeding from the summit of the third 

 series of plates, without tentacles." And he says further: "The 

 Crinoids constituting this genus have been referred to Poteriocri- 

 nus and Cyathocrinus, the structure of which genera are some- 

 what different. The two species given as Poteriocrinus in vol. i., 

 Palaeontology of New York, should be placed under this genus, 

 having the same simple structure and arrangement of plates, 

 arms, etc." 



The above description is so indefinite, that it includes almost 

 every genus of the Cyathocrinidae ; the only character mentioned 

 of generic value is the absence of pinnulae, in which it agrees, how- 

 ever, with Cyathocrinus and Dendrocrinus. The typical speci- 

 mens which Hall used for description were most unsatisfactory, 

 that of H. parvus being evidently a very young individual, Avhile 

 those of H. cylindricus are very imperfectly preserved. In Hall's 

 corrected list of the New York fossils he seems to have given up 

 both Dendrocrinus and Homocrinus, as he groups the species of 



