300 GENERAL SUMMARY TO 



be very desirable to obtain and examine a large series of specimens of the same species, 

 both recent and fossil, at different stages of development (as has been done by Herr Friele 

 for Wald. cranium and W. septigera), a study that will repay those naturalists who 

 may be able to procure the necessary material. 1 



Embryology of the Brachiopoda. 



During many years the Brachiopoda have been considered as constituting a portion 

 of the sub-kingdom Molluscoidea, and this view is still adhered to by many distinguished 

 naturalists ; but, since the study of the embryo of the Brachiopoda has been undertaken 

 by some of our most eminent zoologists, much uncertainty has prevailed and many 

 differences in opinion have been expressed with respect to the true position the Brachiopoda 

 should hold among the Invertebrata. 2 



It will not be possible in this Summary to enter into very minute details in connection 

 with the development of the Brachiopod from the egg up to its adult condition, but the 

 endeavour will be made to give some of the principal results obtained and opinions 

 entertained in connection with the subject, one of such great importance and so ably 

 worked out. 



In 1853 Sir Richard Owen, in the chapter " On the Anatomy of the Terebratula," 

 which he kindly added to my General Introduction, briefly described the generative 

 system as well as the egg of Lingula, with seven figures. He remarked that the 

 generative organs presented the same form in all the individuals of the different 

 species of Terebratulce examined by him, and that this form corresponded with that of the 

 pallial sinuses in which they seem to be situated. He believes that the individuals of 

 this genus are dioecious, not, as he formerly supposed, simple hermaphrodites. The 

 embryos of Terebratula, Terebratulina, Waldlieimia, Argiope (Cistella), Thecidium, Discina, 

 and Lingula were examined and described. 



In 1849 E. Forbes says in his 'British Mollusca,' that in the Brachiopoda the sexes are 

 distinct and that the organs of the sex are attached to the mantle. The ova of Terebratula, 

 writes Woodward in his 'Manual of the Mollusca/ p. 212, Ed. 1856, " are developed within 

 large veins, which they accompany as far as the secondary branches. In the Rhynchonellidcs, 

 and probably in the Orthidce, the ovaria do not extend to the venous trunks, but occupy 

 large sinuses on each side of the body ; in Discina and Lingula they (or the testes) fill the 

 interstices of all the viscera but do not appear to extend into the mantle." Hancock stated 

 that in Waldheimia Australis the genitalia " are formed of thick bands somewhat 



1 Observations on the development of the loop have been published in my " Report on the Brachiopoda 

 dredged by the ' Challenger ' Expedition," 'Zoology,' part 1, 1880. 



2 In 1789 — 1792 Bruguiere described the Brachiopoda under the name of "Vers testaces," testaceous 

 worms. 



