THE BRITISH FOSSIL BRACHIOPODA. 301 



convoluted and branched ; they are full of yellow colour, and are thrust into the trunks 

 and main branches of the great pallial sinuses. There are four of these bands, two 

 in each lobe; those in the dorsal lobe are single and occupy the outer or lateral 

 sinuses, extending from behind the attachment of the occlusor muscles to within a 

 short distance of the anterior margin of the mantle ; their posterior extremities reach to 

 the perivisceral chamber. The ventral pair extend as far forward as the dorsal, and are 

 double ; that is, each forms a loop, the free extremities of which pass into the outer and 

 inner sinuses of the same ; the looped portions lie within the perivisceral chamber, at the 

 sides and below the pseudo-hearts or oviducts." 1 The organs themselves, the same author 

 continues, vary considerably in size and " in the extent of their ramifications, chiefly on 

 account, apparently, of their state of development, though not entirely so ; as even where 

 the ova are mature there is occasionally a remarkable diversity." Hancock entered minutely 

 into the subject in connection with the reproductive system, and to this the reader is 

 referred. He considered Lingula at least to be androgynous or monoecious, and he infers 

 from analogy that both sexes are combined also in the Articulated Brachiopoda. 



Prof. H. Lacaze-Duthiers, in his admirable memoir on the ' History of the Thecidium 

 mediterraneum 2 treated in great detail of the organs and mode of reproduction. He 

 wrote that, as the Brachiopoda known up to the present time are all attached, the connec- 

 tion of the two sexes becomes impossible, and that in this group the conditions of fecun- 

 dation must be left to hazard. The genital glands of the two sexes, he says, are borne by 

 different individuals ; and he had ascertained that in Thecidium the separation of the sexes 

 is shown by a constant character or difference in the adult shell. " In vain have I sought 

 for differences in the shell in other genera and species which would enable me to find out 

 which shell belonged to a male or to a female individual." This would appear to be 

 different in Thecidium ; however the distinguished French zoologist seems to have proved 

 that hermaphrodism does not exist in Thecidium, as the distinction of the sexes is as 

 defined as in the more highly organised animals. 



Next, in 1872, came the admirable researches of Prof. E. Morse on the development 

 of Terebratulina caput-serpentis. 21 He mentioned that to Oscar Schmidt is due the credit of 

 giving the first figure of a larval Brachiopod (in the ' Zeitschrift fur Naturwissenchaften,' 

 1854, p. 315). Therein he gives a description of the embryo of some species of Tere- 

 bratula collected in the North Sea, with a simple figure. In this the embryo shows a deep 

 constriction in the centre, the free or cephalic portion being wider than the posterior half, 

 which is abruptly truncated at the end ; and he infers, and rightly too, that at this end the 

 embryo becomes attached. Prof. Morse described the eggs and their mode of development 

 with admirable preciseness and detail; and added, "The eggs are discharged from the 



1 " On the Organisation of the Brachiopoda," ' Phil. Trans.,' vol. 148, p. 817, 1858. 



2 ' Annales des Sciences naturelles,' 4th ser., vol. xv, p. 302, 1861. 



3 "On the Early Stages of Terebratulina septentrionahs ('Boston Soc. of Nat. Hist.,' vol. ii, 1869; 

 ' Annals and Mag. of Nat. Hist.,' 1871, p. 414; "On the Oviducts and Embryology of Terebratulina " ('Ann. 

 Journ. of Sc. and Arts,' vol. iv, 1872 ; " Embryology of Terebratulina" (' Boston Soc. of Nat. Hist.,' 1873). 



