452 Transactions. 



Symbolothyrid (from crvfxfSoXi], the part that meets, the joiuing, the 

 end).* Symbolothyrid is the foraminal position in many Atremata, in 

 early forms of the Telotremata, and is also found in Plafystrophia. 

 " Coenothyrid " (from Kutrds, shared in common) also suggests itself, but 

 would have to be rejected to prevent confusion with Coenothyris . it 

 would be inadvisable to have to say that Coenothyris was not coenothyrid 

 but gastrothyrid. In regard to the symbolothyrid foramen there is the 

 possibility of its greater portion being in one valve and the lesser part in 

 the other. Such cases could be described as symbolothyrid inclining to 

 gastrothyrid or to notothyrid, as the case might be. 



Some special developments in the structure and conditions of the foramen 

 now seem to merit distinctive terms. Tlie foramen is in the form of a tul)e 

 extending into the valve : the shell is therefore 



Siphonothyrid (frt^wr, a tube), as in the Si]>lionotretidae and in 

 Syringotkyris. A siphonothyrid shell is to be distinguished from one in 

 which the whole beak projects forwards as a little tube well separated 

 from the dorsal umbo. This is a case of a tubular beak, and is found, for 

 instance, in Terebratula wrighti Davidson, of the Bajocian, to which I have 

 given the generic name Tubithyris.'f A greater developnient still of the 

 tubular beak is seen in Lyra meadi {Terebrirostra), where the beak is 

 produced into a long pipe. This may be termed a fistulale rostrum or beak 

 {fistula, a pipe). It is the whole beak which is under observation, not 

 merely the foramen ; that, I expect, is e])ithyrid attrite, but I have no 

 example of this interesting and rare shell. 



Cryptothyrid (kputtto?, hidden) is a term now suggested to denote a 

 foramen hidden or concealed by the beak, as in the case of Athyris, whicli 

 originally obtained its name (a, not; ^upt?, foramen [window]) because it 

 was supposed that it lacked a foramen. It is quite jiossible that the 

 pedicle was almost functionless. 



In Productus the pedicle certainly was functionless, the foramen being 

 more or less sealed up, the animal having no need to use the pedicle, as it 

 could anchor itself by its long spines. For this condition the term 



Clistothyrid (K-Acto-rd?, shut up) seems suitable. 1 would prefer to write 

 it " cleistothyrid," to signify that the first / is to ])e [n'onounced long, 

 but such is not the rule that has been laid down. 



I am under the impression that a minute Rhynchonellu of the Upper 

 Inferior Oolite to which I have given the name NannrrhynchiaX is clisto- 

 thyrid. The foramen seems to be closed, but ol)servation in regard to this 

 feature of so small a shell is difficult. This tiny shell has a hirsute test, 

 sufficient, perhaps, to anchor so small an object. 



A further development of the clistothyrid condition is when the foramen 

 is not only closed with calcareous matter, but the shell is cemented down 

 to the object of attachment. For this the term 



Calcithyrid (calx, lime) seems obvious. Objections to it as a barl>arism 

 are sure to be made ; but they neglect the fact that a word is for use first 



* I have already proposed for this position of the foramen the term amphithi/rid 

 (Brachiopoda, Australian Antarctic Expedition, 1911-14, Scientific Reports, ser. C, vol. 4, 

 pt. 3, p. 20, 1918). ]\Ir. Buckman, who has seen the manuscript of my paper, but 

 is apparently unaware that it is published, writes that the name is not as happy 

 as it might be, as the Greek aiJ.(pLdvpos means " with door or both sides, a double 

 entrance," suggesting a foramen in each valve. As there is no definite law of prioritj' 

 in such terms, it is preferable to use symbolothyrid. — J. All.\n Thomsox, 25/6/19. 



f Records Geol. Surv. India, vol. 45, p. 78. 1915. 



j Gen. -Jur. Brachiopoda, p. 2, 1914. 



