CRUSTACEA. 215 



ranges of plates appears to be a matter of uncertainty and probably also of 

 variation. Turrilepas Wrightianus, l>e Koninck, has tour ranges ami Barrande 

 has expressed the impossibility of ascertaining from his specimens of Plumulites 

 the exact number of these rows, regarding it as not less than lour and rarely 

 so few. In Lepidocoleus, Faber, there appear to be but two ranges of plates. 

 In none of these genera has the character of the upper extremity of the animal 

 been ascertained. Sirobikpis spinigera may present a similarity to Turrilepas 

 (Plumulites) in the numerical arrangement of its parts, but it presents an 

 association of characters which separate it from either of those genera. In 

 recognizing the cirriped character of this fossil, it is difficult to conceive how 

 such a body, capped at the anterior extremity by a circular conical plate over 

 which the adjacent plates are lapped, could have served as anything but the 

 capitulum of the animal. There is no such difference in the character of the 

 plates as would allow some of them to be regarded as peduncular and some as 

 capitular, and no evidence that any scaly peduncle was attached beneath the 

 plates. On the contrary the whole association of plates appears to represent a 

 simple and uncomplicated primary type of lepadiform capitulum, less condensed 

 and modified than in recent representatives. Scalpellum, Lepas, Ibla, etc. 



Distribution. Hamilton group. In the upper shales near Menteth's Point. 

 Canandaigua lake. 



TURRILEPAS. Woodward. 1865. 

 Turrilepas flexuosus, n. sp. 



PLATE XXXVI, PIC 1. 



A SINGLE minute plate is characterized by the following features: Outline 

 obliquely lanceolate ; nucleus apical ; a longitudinal furrow, lying just behind 

 the middle line of the valve, begins at one-third the distance from the apex 

 to the basal margin, becoming broader and deeper as it proceeds, its slope 

 on the anterior side being much stronger and more abrupt than on the 

 posterior. 



