GENUS OVULITES. 179 



Genus II.— Ovulites (Plate XII, figs. 9, 10). 



284. History. — The name Oveoliks was applied by Lamarck in 1801 (lvii) to a minute 

 fossil, abundant in the " Calcaire grossier," which has very much the aspect of a bird's gge 

 in miniature ; and this name was subsequently (lix) altered by him to Ovulites. Under this 

 latter designation the genus has been adopted by various systematists, most of whom, how- 

 ever, have seemed uncertain as to its true place, which has generally been supposed to be 

 among Zoophytes. And even D'Orbigny has included it among Foraminifera only in his 

 most recent systematic publication (lxxiv) ; ranking Bactylopora (^ 187) in close proximity 

 to it! 



285. External Characters. — This beautiful little fossil type is the largest of the mono- 

 thalamous Foraminifera ; its one segment, which is usually about the size of a mustard seed, 

 equalling in bulk the entire polythalamous shells of ordinary 3fitioIa, Motalia, &c. The 

 typical form of the shell is ovate, with an aperture at each end, so as to give it a striking 

 resemblance to a " blown" bird's egg (Plate XII, fig. 9) ; while the pearly aspect which it 

 often presents caused Lamarck to confer upon it the specific name maryaritula. Various 

 aberrant forms, however, present themselves ; most of them being the result of elongation 

 with or without occasional constriction. Thus a moderate degree of elongation with con- 

 strictions at intervals (a sort of foreshadowing of division into chambers) gives to some 

 specimens the aspect of sausages ; whilst a greater degree of elongation will produce a long 

 straight tube (the 0. elonyuta of Lamarck) ; and this tube may be clavate at one or both ends, 

 so as to resemble a drumstick or a life-preserver (fig. 10). In every case there is a large round 

 aperture at each end ; and this is the most distinctive character of the genus. The cavity is 

 simple and undivided, though sometimes narrowed by the constrictions which show them- 

 selves externally. The shell -wall is perforated by large sparse pores ; and these very com- 

 monly open on the surface into minute superficial depressions, which, in some of the 

 elongated forms, are so regularly arranged as to give rise to a delicate hexagonal areolation, 

 having a pore in the centre of each areola (fig. 9, «), — the superficial resemblance thus pre- 

 sented to Bactylopora (^ 124) having probably infiuenced D'Orbigny in his approximation of 

 that most complex type to the simple Ovulites. Specimens that have escaped molecular 

 change present the clear, smooth, glassy appearance characteristic of the hyaline Fora- 

 minifera. 



286. Affinities.— 'YXiQ close relationship between Ovulites and Orhdina is sufficiently 

 obvious ; as is also that between Ovulites and Layena, especially through the distomatous 

 varieties of the latter (f 237), — the coarser texture of the shell, however, and the absence of 

 anything like an everted lip with radiating notches, being marked features of difference. The 

 elongated forms may be considered as related on the one hand to Spiriltina, and on the other 

 to these vermiculate forms of the Rotaline PulvinuUna which have wildly growing, attenuated, 

 and prolonged chambers. 



