EARLY STAGES OF TEREBRATULIXA. 37 



bilateral lophophore of the superior, or Phylactolrematous Polyzoa. The brachial fold, a 

 delicate membrane bordering the lophophore, immediately within which the cirri spring, 

 as seen in Lingula and Discina, may properly be compared to the calyx in the higher 

 Polyzoa. Still later the presence of a distinct fold bordering the mouth, very pliant and 

 active, may be compared as to function and position, with the epistome of the Polyzoa, 

 though not occupying an homological position in regard to flexure of intestine. It would 

 appear that the membranes suspending the stomach and intestine in the perivisceral cavity, 

 have some relation to the funiculus in the Polyzoa. In Paludicella there are two flexible 

 cords connecting the stomach and the endocyst, called by Allman the anterior and posterior 

 funiculus, to which are attached respectively the ovary and testis. In Lingula and Dis- 

 cina we find the reproductive organs attached to bands, that connect the stomach and 

 intestine to the perivisceral wall. In Alcyonella the ovary arises from the endocyst, and 

 likewise in Terebratulina and allied genera we find the mantle, or endocyst, holding the 

 reproductive organs. 



The early appearance of the divaricator muscles in Terebratulina would justify Mr. 

 Hyatt in his views, that these muscles represent the retractors of the Polyzoa. 1 



The combination of the stomach and intestine in their early stages, with the presence 

 of hepatic cells lining their inner walls, and the presence also of a cardiac valve or con- 

 striction, all recall similar parts in the higher Polyzoa. 



That these relations may be carried farther, there is no reason to doubt. Fritz Miiller 

 has noted in an early stage of some species of Discina (though from observations I have 

 made in Lingula pyramidata, the embryoes examined by him are as likely to belong to 

 this genus, as to Discina) several sets of seta), which project from the body and are capa- 

 ble of locomotion. F. A. Smitt 2 has noticed in the development of Lepralia Peachii, a 

 cluster of six bristles bent at their points, that from time to time were drawn in and again 

 thrust out. 



With propriety may also be suggested a certain parallelism between the leading groups 

 of the Polyzoa and the Brachiopods. We have fonns, like Lepralia, attached by one 

 region of their shell, this shell being calcareous and exhibiting minute punctures, which 

 have been compared to similar markings in certain Brachiopods. So among the latter 

 group do we find forms attached, as in Thecidium, and some species of Productus ; and 

 generally the articulate Brachiopods might be compared to such forms as Lepralia, while 

 on the other hand such genera as Pedicellina, with its long, pliant and muscular stalk, or 

 Loxosoma, with a stalk highly retractile, may be compared to Lingula. The limits or 

 intentions of this paper will not allow any considerations regarding the relations of the 

 Brachiopods with the other groups of the animal kingdom. I have elsewhere 3 expressed 

 my belief that they are true articulates, having nearer affinities with the Vermes ; and in 

 view of the above relations of the Brachiopods with the Polyzoa, it is interesting to remark 



A. Hyatt. Observations on Polyzoa, suborder Phylacto- 8 The Brachiopoda, a revision of Annelida, American 



laemata. Proceedings Essex Institute, vols. IV, v. Salem, Journal Sc-ience, July, 1870. Reprinted in Annals and Mag- 

 Mass, azine of Natural History, London, no. 33, vol. VI, 4th series. 



8 Om Hafs-Bryozoernas utveckling och fettkroppar. Of- 

 versigt af Kongl. Vetenskaps-Akademiens Forhandlingar. 

 Stockholm, 1865. 



MEMOIRS HOST. SOC. KAT. H18T. VOL. II. 10 



