76 Transactions of the Royal Microscopical Society. 



guide, such a multiplicity of names is a stumbling-block, or at least 

 useless. How the Cristellarians have fared in books, the following 

 Table will show, and at the same time it will help us to fix the few 

 rightful names which the chief varieties can claim, and whereby 

 they may be referred to as recognized typical forms. By " Cristel- 

 larians " I mean the more or less coiled varieties of Nodosarina 

 raphanus (taking that as the type species), and admitting a limited 

 use of binomial appellations for these varieties. 



In the following Table of the bibliography of the Cristellaridea 

 from the time of Linne to 1841, a great number of the most 

 important recent and fossil forms of this group are noticed. The 

 range of selected forms takes us from well-developed Marginulinee. 

 to Flanularise. Multitudes, however, of weak or merely Dentaline 

 Marginidinie are passed unnoticed. The " Robulina " of authors 

 is merged with Cristellaria on account of the interchangeableness 

 of the character of aperture in nearly all the nautiloid varieties ; 

 as may be seen in some of the best figures given by D'Orbigny, 

 Eeuss, and others, the two kinds of aperture are merged in one. 

 Indeed, Dr. Carpenter has of late years found that both the round, 

 radiate aperture and the triangular orifice exist together in some 

 Cristellariai from the deep Atlantic. 



Gradations of the Cristellaridea. — Taking up the partially 

 coiled Nodosarinx {MarginuUn^), leading from Nodosaria to Gris- 

 tellaria, we find that Margimdina Wehhiana, D'Orb., Gristellaria 

 subarcuatula (W. and J.), and Cr. gihba, D'O., are examples of 

 such gradation of form. Various specimens with different degrees 

 of ornamentation have been figured, described, and named. Gr. 

 rotulata is the simple, completely discoidal form. Smooth, it is 

 Imvigatula (W. and J.) ; subumbonate, depressula (Montagu) ; 

 limbate and umbonate, querelans (De M.) ; limbate and tuberculate, 

 tuhercidata and elegans, D'O. With but few chambers (necessarily 

 triangular), and limbate, it is virgata, D'O. If thick and opening 

 out transversely it becomes Italica, Defr., navicula, D'O., &c., 

 and is liable like others to grow on straightwise and become 

 elongate. 



If the simple Gristellaria has a marginal ridge, keel, or crest, 

 it is cuUrata (De M.) ; large -chambered and umbonate, cassidata 

 (De M.) ; limbate with beads (or granulate on the septa), papillosa 

 (F. and ]\I.). If swollen, cultrata becomes acutauricidaris (F. and 

 M.), a large and keeled Italica. If the cidtrate form has many 

 small chambers, it is carinata, D'O. ; if the many chambers be 

 much curved and rather vorticial, we have D'Orbigny 's (Bohulina) 

 Soldanii (his Grist. Soldanii is a smooth, limbate cassis) ; if the 

 chambers be very close set, falciform, and vorticial, we have vortex 

 (F. and M.), and orhicidaris and imperatoria, D'O., according to the 

 amount of keel and umbones. "When the Gristellaria retains the 



