Report of the State Geologist. 



r oX\ 



cirri, and while in this condition the segmentation of the embryo 

 is effected. It is not known at precisely 

 what stage of development these embryos 

 are set free from the 

 suspensory cirri and 

 emitted into the outer 

 chamber of the valves. 

 In a specimen of 

 Lmgula lamellata 

 from Upper Silurian, 

 of Hamilton, Ontario, 

 the pallia! cavity has 



/i 



been found filled with 



ova ; and (Ehlert cites FlG 195 . 



Xi 



mil)) 



ova ; ana l&hlert cues Flo rj ,^ mbyr ,-p uch of Laca- 



a Specimen Of StetNGO- zclla P"* 1 * broken, exposing 



/ a r • j j i r\ clusters of segmented embryos 



CEPHALUS (Middle JJe- attached to the suspensory 



vonian) in whose c?lia (Lacaze-dcthiers.) 

 valves were found a number of embryo 

 shells, which 

 would indi- 

 cate that de- 

 velopmen t 

 had t a k e n t 

 place in this 

 chamber. An 

 accelerated 



no. 194-Transven* section of growth of the Fia 196 _ Two embryos of LacazHla attached 

 mantle of Magellama aus- - .. _ 



trails, a, pallial sinus; b, reproductl V e to the suspensory ciha. (Lacaze-Duthiers ) 



genital organ; c, paiiial or p- a ns and the perfection of their function 



lacunes; d, bases of paUial ° x 



caeca. (Hancock.) is shown in certain species of Terebratella, 



which are capable of reproduction during the adolescent maga- 

 diform and magaselliform stages, thus perpetuating a more 

 primitive race which does not attain the characters of the adult 

 Terebratella. 



Development.* 



From the fertilization of the ovum to that stage which may be 

 regarded as terminating the embryonic period, the developing 

 brachiopod passes through the conditions of 



* Our knowledge rf the embryogeny of the living brachiopods is due to Owen. Hancock. 

 Davidson, Morse, Kovalevski, Lacaze-Dutbiers, MOller, Shipley and Brooks, and is pretty 

 much restricted to the genera Terebratulina, Liothyrina, Cistella, Lacazella and Glottidia. 

 The most important contributions upon the morphogeny of the brachiopod shell, are those of 

 C. E. Bekcher. 



85 



