ANIMALS. 19 



In his paper on the " Recent Polythalamia and Infusoria of North and South 

 America,"^ Professor Ehrenberg has placed amongst the Polygastrica a spiral, 

 foraminated, unchambered, six-whorlcd shell, from Vera Cruz, with the above-cited 

 characteristics. The specimen having several young shells within it (passim testulis 

 pullis foeta), received the appellation of Sj). vivipara. Mr. Williamson, in his paper on 

 " Some of the Microscopical Objects found in the Mud of the Levant, &c.,"2 notices and 

 figures a minute, spiral, transparent Foraminifer, having no trace of septa, which, except 

 that it contains no young shells, appears to be identical with Professor Ehrenberg's 

 species ; and at page 87 Mr. Williamson notices how closely the specimens he has 

 seen resemble the one found by the Rev. P. B. Brodie in the Lias, and figured and 

 described by Mr. Strickland, in the ' Geol. Journal,^ vol. ii, p. 30, as Orbis infimiis. 



We have from the Lias a cast in pyrites of this little spiral shell, ^, inch diameter, 

 one surface concave, the other nearly flat, composed of six volutions partially covering 

 one another, convex on their outer, and concave on their inner or enveloping surface ; 

 a portion of the shell, soft, white, and apparently destitute of foramina, is still adherent, 

 especially between the volutions ; the pyrites in the inner whorls is somewhat 

 mammillated, and has some irregular transverse scorings, but no decided evidence of 

 septa exists. 



A specimen from the Miocene Sand of Bordeaux, ^ inch diameter, has six sub- 

 cylindrical volutions, with a central space, and (mounted in balsam) exhibits an 

 appearance that at first sight seems to be the result of concamerations ; but on closer 

 examination, the outer wall of the volutions that have been covered by the external 

 whorls seems to be perforated by large pear-shaped passages ; this appearance is more 

 visible on one (the concave) surface than on the other (the flat) surface of the shell, 

 and is the result of surface-markings. The flat surface is sub-concentrically marked 

 with coarse, rounded punctations, and the concave surface bears a series of large pear- 

 shaped pits^ along the sutures of the volutions, and a cluster of punctations on the 

 central space. The shell of this individual is not foraminated as Professor Ehrenberg's 

 and Mr. Williamson's specimens are described to be.* 



Although, according to these authors, the shell of the recent specimens is more or 

 less perforated with foramina, that is, beset with transparent points,'' a character 

 generally found amongst these microscopic, shelled Acrita, yet the absence of septa, or 

 rather of the evidence of this little microzoon having been built up of a succession 



1 Abhand. Konig. Akad. Wissenschaft. Berlin, 1841, p, 442. 



2 Page 45, pi. ii, fig. 34, printed from the Manchester Lit. Scient. Soc. Mem. 1847. 



* Formed apparently by regular depressions on the enveloping edge of the investing whorl. 



•* It is just possible, however, that transparent pittings have been regarded as foramina in these as 

 in other instances. (See note 6, page 15.) 



^ For the same reason, viz. its punctated surface, the Bordeaux specimen has some claim lo an alliance 

 with the Foraminifera. 



