Professor Rupert Jones — Isochilince from N. America. 303 



vol. xlvi (1890), pp. 545, 550, and 551, aslsochilina Ottawa, Jones.^ 

 Variety, (1) occurring abundantly on the bed-planes of a piece 

 of thin-bedded limestone, from a large block in Sussex Street, 

 Ottawa, and probably belonging to the Chazy formation (upper 

 portion) ; (2) constituting, with a few bivalve Mollusca, the 

 greater part of an easily broken grey limestone from Nepean, 

 Ontario, Canada, belonging to the Chazy formation. Both were 

 sent from Canada by Mr. Henry M. Ami, F.G.S., of the Canadian 

 Geological Survey. 



We have to note that the specimens of IsocMlina Amiana and its 

 variety insignis, described by Mr. E. O. Ulrich in the Journ. Cincin. 

 See. Nat. Hist., 1891, pp. 180 and 181, pi. xi, figs. 12a-c 

 and 13, were also derived from a piece of Chazy rock found by 

 Mr. H. M. Ami in Sussex Street, Ottawa, and given by him to 

 Mr. Ulrich ; and they are therefore from the same source as that 

 of the variety of I. Ottawa mentioned above. It was carefully 

 illustrated as var. intermedia in the Contrib. Canada Micropal., 

 part iv (1891), pi. x, figs. lOa-6, lla-6, and a copy of this 

 plate had been forwarded to Mr. Ulrich, as explained in the footnote 

 at p. 181 of his memoir above mentioned. Mr. Ulrich was 

 satisfied, according to that footnote, that the figures named by me 

 IsocMlina Ottawa, var. intermedia, must have been drawn from such 

 specimens as his I. Amiana ; indeed, both came from Mr. Ami, of 

 Ottawa, as fullj' explained. 



The Ostracoda in the hand-specimens from Hamilton, Nos. 1 and 2, 

 very definitely represent the group of Isochilince allied to J. Ottawa 

 and I. gracilis, enumerated in the following catalogue of the known 

 IsocMlince, many of these being either allies, subspecies, varieties, 

 or mutations of /. Ottawa, especially those marked " 1-13," the 

 many minor difi'erential features being rarely sufiicient to separate 

 them specifically. 



Catalogue of the known Isoghilin^. 



1856. Leperclitia margineta (?), Keyserling [afterwards IsocMlina grandis, 

 Jones] : Ann. Mag. Nat. Hist., ser. ii, vol. xvii, p. 91, pi. vii, 

 figs, lia-d. 



(1) 1858. Leperditia (subgenus IsocMlina) Ottawa, sp. nov. : Ann. Mag. Nat. 



Hist., ser. iii, vol. i, p. 248, pi. x, figs. \a-c. Calciferous 

 Sandrock, Grenville, Canada. And Geol. Surv. Canada, Org. 

 Rem., 1858, p. 97, pi. xi, figs, \ia-c. 



(2) 1858. Leperditia (subgenus IsocMlina) gracilis, sp. nov. : ibid., figs. 2a-d. 



White House Papers. Trenton Limestone or Bird's Eye Limestone : 

 Isle Jesus, Canada. And Ann. Geol. Surv. Canada, Org. Rem., 

 1858, p. 98, pi. xi, figs. 15a-^. 



(3) 1860. IsocMlina gracilis, Jones: Month. Microsc. Journ., vol. iv, pp. 185 and 



191, pi. Isi, figs. 18a-e. Lower Silurian: Canada. 

 1881. IsocMlina grandis, Jones {_non Schrenck] : Ann. Mag. Nat. Hist., 



ser. v, vol. viii, p. 347. 

 1881. IsocMlina Jonesi, Wetherby: Journ. Cincin. Soc. Nat. Hist., vol. iv, 



p. 42, pi. ii, figs. 7 and 7a. Trenton Limestone: Kentucky. 



^ Ann. Mag. Nat. Hist., April, 1858, p. 248, pi. x, fig. 1— not so well figured 

 there as on later occasions. 



