224 FAMILY GLOBIGERINIDA. 



he had before him a specimen of the type I am about to describe, since he distinctly 

 notices, both in his description and in his rude figure, that cellulation " sur divers plans" 

 which gives to its vertical section somewhat the appearance of that of a Nummulite. 

 No sucii appearance is presented by vertical sections of Calcar'uia ; whilst, as will pre- 

 sently appear, Tinojjorus is made up of several layers of cells superimposed one upon another ; 

 and although its relation to Nummulina is really remote, yet the resemblance in aspect pre- 

 sented by vertical sections of the two may easily seem, to such as are unacquainted with the 

 real meaning of their respective appearances, sutRciently close to justify the parallel. With the 

 T. baculatm of Montfort it will be shown that we must associate, on account of its close 

 structural relationship, a type which has been described (lxxix) under the generic designation 

 Orbitolina, since it may be comprehended in the very vague definition given of that genus by 

 D'Orbigny (lxxiv) ; and this type is the representative of an extensive series of forms, both 

 recent and fossil, to which the same definition applies, and to which the name Orbilolina has 

 been assigned (loc. cit.) by Messrs. Parker and Rupert Jones. Now there is a very grave 

 objection to such an employment of the term. According to the usage of many systematists, 

 Orbilolina would be nothing else than the appropriate distinction of the recent forms of Orbi- 

 tolites ; and even to such as do not accept this usage, the close similarity of name would 

 assuredly suggest the existence of a structural relationship. But it will presently become 

 apparent that no such relationship exists, the essential structure of the so-called Orbilolina 

 being altogether different from that of Orbiloliles, and no real resemblance existing between 

 them except as regards their plan of growth. Hence it seems very desirable to discard the 

 name Orbilolina dXiogtiher ; and since another form of the same type had previously been 

 distinguished by De Montfort, his name Tinoporus may fairly claim to be substituted for that 

 of D'Orbigny. 



391. As the genus Tinoporus presents itself under a considerable variety of external 

 forms, I think it desirable in the first instance to describe an example that presents what seem 

 to me the essential features of its structure, and is at the same time free from those complica- 

 tions by which those features are elsewhere masked.. Such an example I find in the forms 

 which have been described as varieties by Messrs. Parker and Rupert Jones (lxxix) under 

 the designations Orbilolina vesicularis, 0. conycsta, and 0. Icevis ; these, as I do not hold their 

 differences to be of any account, I reunite under the designation Tinoporus vesicularis.* 



392. Tinoporus vesicularis : Exlemal Characlers. — -The largest examples I have 

 seen of this type present the form of a short truncated cone, much resembling the lower half 

 of a sugar-loaf (Plate XV, fig. 1), having its margins rounded off, and attaining at the base a 

 diameter of about l-lOtli* of an inch. The base commonly exhibits a slight central depres- 

 sion. Sometimes the cone is more depressed, and spreads out more widely at the base ; and 

 in this case the basal concavity is usually wider and deeper. The examples I have seen from 



* In my previous description of tliis type (xvi), I designated it T. Icevis ; but I thiuk it better to 

 substitute the specific designation vesicularis, under which one of its varieties has been described else- 

 where, as better agreeing with the generic name; — " a smooth" " stick- bearer" being a contradiction in 

 terms. 



