472 Reviews — J. F. Whiteaves' Fossils of Manitoba. 



muscular impressions, which, however, are very indistinctly defined, 

 were probably longer." 



At Lakes Manitoba and Winnepegosis, all the species described in 

 the paper, with the exception perhaps of Gomphoceras Manitobense, 

 and Gyroceras submammillatum, were associated with this Brachiopod, 

 a shell which, in Europe, occupies a definite horizon in the Middle 

 Devonian. 



Although based upon very meagre material, the species referred 

 to the genus Modiomorpha can, it is believed, " be recognized at a 

 glance by its unusually large size and narrowly attenuated form, 

 although it is by no means certain that it is correctly referred to 

 this genus." Since the hinge is not well preserved in any of the 

 specimens collected, the species assigned to the genus Megalodon 

 is provisionally referred to that genus on account of its " strong 

 resemblance in external structure to the M. truncatus and M. rhom- 

 loidalis of Goldfuss from the Devonian rocks of the Eifel." 



Of the two new Gasteropods which are described, viz. Pleuroto- 

 maria goniostoma and Euomphalus Manitobensis, the latter is stated 

 to be one of the most abundant and characteristic fossils of the 

 Devonian rocks at Lakes Manitoba and Winnepegosis. In addition 

 to detached opercula, one specimen has been found in which " the 

 shell is so broken as to show its operculum in situ, though a little 

 displaced from its normal position." 



A remarkable species of Orthoceras is described under the name 

 0. (Thoracoceras) Tyrrellii. It has a marginal siphuncle and is 

 ornamented with transverse plications and longitudinal ridges, each 

 point of intersection of a transverse plication with one of the longi- 

 tudinal ridges being marked by a short, slightly curved spine. The 

 author observes that it " seems to belong to that group of the 

 Orthocerata for which Fischer de Waldheim proposed the generic 

 name Melia in 1829, though, finding this preoccupied, he changed 

 it to Thoracoceras in 1844." Fischer gave as the type of the genus 

 Thoracoceras, Th. vestitum — a species with a rather small, sub- 

 marginal siphuncle, and ornamented with spinose, longitudinal 

 ridges. Although adopted by some subsequent writers, the genus 

 has been variously interpreted. According to Prof. Hyatt, who 

 regards the genus as valid, it includes "all those longicone species 

 in which the ridges become spiny or are roughened by the promi- 

 nence of the transverse striae or ridges," and also such forms as 

 Cyrtoceras corbvlatnm, Barrande, Cyrt. canaliculatum, de Koninck and 

 Cyrt. Puzosianum, de Koninck. The author adopts Thoracoceras, 

 but regards it only as a subgenus of Orthoceras. 



The figure given of Gomphoceras Manitobense certainly bears out 

 the author's statement that the anterior end of its body-chamber 

 appears to be more like that of Poterioceras. The species, howevei', 

 is rather doubtfully referred to the genus Gomphoceras on account 

 of its general resemblance to the G. eximium of Hall. 



Two new genera of Cephalopoda are described, viz. Homaloceras 

 and Tetragonoceras. The former is thus characterized — " Shell con- 

 sisting of a slender tube which is broadly and strongly arcuate-, 

 curved in the same plane and much flattened laterally, its venter or 



