Frof. H. A. Nicholson — New Devonian Fossils. 121 



growtli, which become close set and imbricating towards the margin 

 of the valves. 



The dimensions of a large individual are:— Length, one inch; 

 greatest width, ten lines ; height, eight lines. A smaller and 

 narrower individual has a length of eleven lines, a greatest width 

 of eight lines, and a height of six lines. 



There is no doubt as to the entire distinctness of this species from 

 Lp.iorhynchus muUicosta, Hall, though there may perhaps be some 

 question as to its reference to Leiorhjnchus ; since Hall states that 

 the fold and sinus in this genus never interlock, which they certainly 

 do in some, if not in all, of the examples of this species. In other 

 respects there is a close general resemblance between this and L. 

 multicosta, especially as regards the surface -characters, and I do not 

 think the two species can be generically separated. L. Huronensis 

 is distinguished from L. multicosta by its much more elongated and 

 contracted form, the greater convexity of the valves in the umbonal 

 region, the much more prominent and strongly incurved beak of the 

 ventral valve, the absence of a foramen in the adult, the much 

 greater width and shallowness of the sinus and fold, and the stronger 

 and more crowded lines of growth. I have not seen any example 

 which exhibits the interior. 



Locality and Formation. — Shales of the Hamilton Group, Widder, 

 Township of Bosanquet. (Collected by Mr. Geo. Jennings Hinde.) 



Genus T^niopora, Nicholson. 



Polyzoary calcareous, composed of a flattened linear expansion, 

 which branches dichotomously, and is celluliferous on both sides. 

 Each side of the polyzoary is furnished with a strong median ridge 

 or keel, which has a longitudinal direction, and separates the frond 

 into two lateral halves. The cells have very prominent apertures, 

 and are arranged in from three to five longitudinal rows on each 

 side of the central keel ; the cells of contiguous rows alternating, 

 so that a series of short oblique rows of cells are produced, which 

 diverge from the keel like the barbs of a feather. The margins of 

 the polyzoary are usually plain and non-celluliferous, and the cells 

 are not separated by longitudinal striae or elevated ridges. No 

 fenestrules are present, and the entire frond forms a continuous ex- 

 pansion, within which the cells are immersed. 



Two species of Polyzoa which agree in the above characters are 

 not uncommon in the Hamilton Formation of Western Ontario ; and 

 their structure appears to me to be sufficiently distinctive to entitle 

 them, to be considered as constituting a distinct genus, which I 

 propose to term TcBniopora, from the ribband-like form of the 

 coencecium. The affinities of TcBniopora are clearly with Ptilodictya ; 

 and though there are some important points in the structure of the 

 former which I have been unable to make out, I nevertheless find 

 the external characters of Tceniopora are alone sufficient to warrant 

 generic distinction. One of the chief characters of Ptilodictya is the 

 presence of a striated laminar axis, separating the two celluliferous 

 aspects of the polyzoary. I have not been able to establish clearly 

 either the absence or presence of such an axis in Tceniopora, but my 



