294 G. F. Matthew — New genus of Cambrian Pteropods. 



thus formed a shorter cone than Camerotheca), and in having a 

 firmer and, as preserved in the shales, rounder side, where it has 

 the support of the lateral diaphragms. This feature of the 

 endo-skeleton is most distinct in two species, varieties of which 

 are found in the sandstones near the base of Div. 1 of the St. 



John Group. The shells of these pteropods are here found 

 scattered over the surface of the sandy layers of an old sea 

 bottom, close to the shore line ; and occur mingled with the 

 material forming the casts of worm burrows and imbedded in 

 phosphatic nodules. They thus occupied locations where in 

 later formations lamellibranchs might be looked for : but the 

 remains of numerous individuals of the species of this genus 

 are also found in fine shale at a higher horizon, showing that 

 the genus inhabited deeper waters as well. 



Further particulars of these species will be found in an arti- 

 cle read before the Eoyal Society of Canada, 1885. 



Reference to the figures : 



la. Diplotheca acadica Hartt, sp. var. crassa, dorsal view, showing the dia- 

 phragms of the endoskeleton. The diaphragms near the aperture and the septa 

 near the apex are exposed by the abrasion of the shell. 



lb. Same, transverse section, showing the body cavity partly enveloped by the 

 phragmated part of the tube (represented by the shaded area). 



2a. Diplotheca Hyaitiana, |, vertical section, showing the septa at the apex of 

 the tube, and the diaphragms at the side. 



2b. Same, section of a flattened shell, from front to back, showing the curved 

 apex. 



2c. Diplotheca Eyattiana var. caudata, ^, showing the annulated flexible tubule 

 attached to the apex. 



3a. Phragmotheca Bohemica Barr., showing along the axial line the place where 

 the phragmated sheath is found and the closeness of its diaphragms — figured for 

 comparison. 



3b. Same, transverse section of the shell, the shaded portion marks the narrow 

 phragmated sheath. 



St. John, N. B., July, 1885. 



