74 Transactions of the Roijal Microscopical Society. 



skeleton " so highly perfected in some Rotalina. When elhptical 

 in section (compressed) Lagense lose the ronndness of their orifice, 

 which becomes a slit, giving the quasi-subgeneric name of Fissurina. 

 The triangular and quadrangular forms of some compressed Lagense 

 have given rise to other such terms. AmjpJiorina is a Lagena open at 

 both ends. When the apertural tube is turned inwards, the shell is 

 Entosolenian ; when the tube is present and protrudes as usual, it is 

 Ectosolenian. Some Pohjmorphinw have an inverted tube also. 

 The shells of Pohjmorphina and Uvigerina have much in common, 

 one with another, and consist essentially of Lagenoid chambers 

 heaped alternately, with certain habits of growth, but Lagenidal in 

 ornament and aperture. Nor are Bulimina and its subgroups far 

 removed from the same series. 



Nodosaria, Cristellaria, &c. — A succession of Lagenoid cham- 

 bers, in a straight hne, constitutes a Nodosaria. The chambers 

 being like a series of bottomless, or at least perforated, flasks, set 

 one on another. They differ considerably in their overlap, from 

 merely encircling the previous apertural tube, or neck, to investing 

 the whole front of the previous chamber. The terminal aperture 

 is either a round hole, with its border cut up into minute radial 

 laminas, or a produced tube, sometimes lipped, and occasionally en- 

 circled, as in some Lagenm, with a little spiral cord. The ornament 

 consists essentially of either perfect or intermittent ridges of vitreous 

 shellmatter, rarely joined by cross lines; often produced into 

 prickles, or dying away in granules ; sometimes represented by 

 diffused granulation, and sometimes reduced to very few sharp 

 crestlike ribs. Slight excentricity of the axis of growth, in the 

 setting-on of the segments, often takes place, simply curving the 

 shell (especially when it does not begin with a strong growth of 

 relatively large and equal-sized chambers), without altering the 

 relative position of the aperture : but this is easily shifted to one side, 

 generally the outer or convex side of the curve, and the chambers 

 become more or less oblique. " Dentalina " comprises both conditions 

 in these usually tapering, bent Nodosarina. There is no straight 

 Nodosaria without its more or less bent congeners ; and these are 

 associated with more and more curved individuals {Bentalinse), 

 until the early chambers are not only excentric in growth, but 

 have a discoidal coil (Marginulims) ; and other associates have 

 gone further in this style of growth, until the whole of their shell 

 is nautiloid (Cristellaria). Thus the smooth Nodosaria radicula 

 has Dentalina communis, Marginulina subarcnatula and Cris- 

 tellaria rotulata as its congeneric associates or varieties ; whilst the 

 ornamented Nodosaria rajjhanus, has D. acicula, M. raplianus, and 

 Cr. costata as varietal associates. N. radicula and N. raphamis, 

 moreover, are so closely linked by graduated individuals, that they 

 are really but varieties of one species of Nodosarina. 



