of Terebratulina septentrionalis. 425 



some species of Discina (though, from observations I have 

 made on Lingula pyramidata, the embryos examined by him 

 are as likely to belong- to this genus as to Discina) several 

 sets of setfe which project from the body and are capable of 

 locomotion. F. A. Smitt* 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 Brachio- 

 pods. We have forms, like Lepralia, attached by one region 

 of their shell, this shell being calcareous and exhibiting mi- 

 nute punctures, which have been compared to similar mark- 

 ings in certain Brachiopods. So, among the latter group, do 

 we find forms attached, as in Thecidium and some species of 

 ProducUis ; 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 king- 

 dom. I have elsewhere f 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 that Leuckart has for 

 a long time placed the Polyzoa with the Vermes ; and in a 

 new edition of the ' Outlines of Comparative Anatomy 'J, 

 Prof. Carl Gegenbaur removes the Polyzoa from the Mollusca 

 and associates them with the Vermes. 



EXPLANATION OF THE PLATES. 



In the acconipauyiug figures m designates the mouth ; e, epistonie ; 

 ce, oesophagus ; s, stomach ; c, cardia ; i, intestine ; /, faeces ; vm, ventral 

 mesentery ; I, liver ; h, hepatic cells ; 0/7, oral groove ; ot, oral tubercle ; 

 d, divaiicator muscles ; lb, lateral gastroparietal bands ; p, pedimcle ; 

 prt, point of attachment of peduncle ; se, setfe ; c?«, pallial caecum • ^, cirri; 

 y, gTanules passiijg to and fro from liver to intestine ; cr, crura ; cl, cal- 

 careous loop ; ex, external shell-layer, of a chitinous nature ; in, internal 

 shell-layer, of calcareous scales ; iqj, hinge-plate ; cp, cardinal pro- 

 cess ; ds, dental sockets ; /o, foramen ; te, teeth of shell ; cs, calca- 



* '' Om Ilafs-Bryozoernas iitA-eckling och fettkroppar," CEfversigt af 

 Kongl. Vetenskaps-Akademiens Forhandliugar : Stockholm, 18G5. 



t "The Brachiopoda a Division of Annelida," American Joiu-n. Sc. 

 July 1870 ; reprinted in Ann. & Mag. Nat. Hist. ser. 4. vol. vi. no. 33. 



J CTrundziio;e der vergleichenden Anatoniie. Zweite umgearbeitete 

 Auflage. Leipzig, 1870. 



