10 



Kuutilus, or ihe' siphonal edye of thut of an Ammonite, can scarcely be 

 misunderstood. Avhile the word perij/herij will suit either indifferently. 



The expression aperture, as applied to these fossils, is jiurposely chosen 

 to descrilie the shape of the Avhorl at or near its outer termination, as 

 vieAved transversely; but not necessarily that of the true outer lip of the 

 shell. The Ae?'(//if of the aperture will be measured from the centre of 

 the periphery of the outer whorl to that of the one which precedes it ; the 

 ividth, at a right angle to the height. 



In descj-ibing the shells of Grasterojjoda, the adjective transverse, Avhen 

 applied to ribs or stria?, is intended to mean transverse as to the whorls, 

 and not as to the axis of the shell. 



To preserve a certain consistency througlnmt, the /le^'^Af of lamellibran- 

 chiate bivalves will be measured, as nearly as possible, in the direction of 

 a line draAvn perpendicularl}' from the hinge line or dorsal inargin, to the 

 opposite or ventral border. The length will be estimated at a right angle 

 to the height, and the width or breadth as equal to the maximum thickness 

 through the closed valves. 



As the valves of the Brachiopoda are respectively dorsal and ventral, 

 the length of these shells will be measured from the beak of the pedicelled 

 valve to its opposite extremity, while the loidth will correspond to the 

 sjjace between the two margins of either valve, at a right angle to the 

 height. 



Throughout these descriptions, the word diameter must be understood 

 to impl}' the distance between two points, as measured on a flat surface. 



Geographical names and others which, according to Dr. Johnston,* have 

 a "rerainiscential evocation," hrtve been freely proposed for fossils which 

 are believed to be new, especially in the case of genera, such as Ammonites, 

 in which the number of sjiecies is already so large that it is almost hope- 

 less to expect to tind descriptive names which are not preoccupied. 



In conclusion, the writer desires to express his cordial thanks to Mr, 

 W. H. Dall, of Washington, who has kindly made and forwarded tracings 

 of ligures as well as copies of descriptions of certain fossils from books 

 not at present accessible in Montreal, and for various critical suggestions; 

 to Mr. F. B. Meek, also of Washington, who obligingly sent photographs 

 of drawings made from the original types of ,species from Yancouver and 

 Sucia Islands, described by him ; to Mr. Eichardson for information as 

 to the exact stratigraphical position and localities of the fossils which lie 

 collected ; and to Mr. A. H. Foord, for the pains he has taken in the de- 

 lineation of the features characteristic of the different species. 



* " British Zoojihytes." Second Edition. Vol. I., paye 1C4. 



