the Nomenclature of the Foraminifera. 231 



These six figures, associated by Batsch as one species, together 

 with the two which follow (16 a, 16 b), are varieties of the type 

 Peneroplis pertusus, differing amongst themselves chiefly in the 

 comparative length and breadth of the chambers and the extent 

 to which they are coiled. Whilst insisting on the specific unity 

 of the whole of the variations of form to which the type is sub- 

 ject, it is, zoologically, a convenience to recognize certain inter- 

 mediate stages as constituting varieties worthy of distinct name. 

 Thus the extremely dilated, flat, bonnet-shaped condition takes 

 the subspecific name P. planatus, F. & M.; the moderately 

 dilate, central-typical form is P. pertusus, Forskal ; and one of 

 the figures now under notice (15 c) might worthily take its place 

 as a variety, with Batsch's name P. arietinus. In figs, a, b, and c 

 the shape of the shell is determined by the excessively wide, flat 

 development of the later chambers. In figs, d, e, and /the ten- 

 dency is somewhat different, the later chambers leaving the 

 nautiloid portion in a straight cylindrical line; and this tendency 

 reaches its fullest development in the last two figures on the 

 plate (16 a, b). These " Spiroline " forms were recognized by 

 Lamarck and others, but confused with isomorphous varieties 

 of Valvulina and Lituola ; removing these, however, the long 

 crozier-like Peneroplides may retain the term Spirolina (used 

 subgenerically, for the sake of convenience only, not zoologically). 

 The term Coscinospira was adopted by Ehrenberg for a short, 

 stoutish, Lituate or Spiroline form, such a one as figs. 15 d, e,f. 



The wide variation in character presented by specimens of the 

 type now under notice has caused much confusion in the nomen- 

 clature ; and it will not be out of place here to point out some 

 of the forms of Peneroplis referred to and named by the earlier 

 writers, together with the view we take of their value. 



17/5. Nautilus pertusus, Forskal,=Peneroplis pertusus, Forsk. Type*. 

 1781. Nautilus rectus, Spengler,=a. mixed lot (Peneroplis and Arti-~\ 



culina). 

 1/88. Nautilus Lituus, Gmelin,=Peneroplis (Spirolina) Lituus, Gm. 

 1/91. Nautilus (Lituus) arietinus, Batsch,=Peneroplis arietinus. 

 1791. Nautilus (Lituus) acicularis, Batsch,=Peneroplis (Spirolina) 



Lituus (Gm.). 



1803. Nautilus planatus, Fichtel cy- Moll,=Peneroplis planatus, F.fyM. 



1804. Spirolina depressa, Lamarck,=-Peneroplis pertusus, Forsk. 

 1804. Spirolina cylindracea, Lamarck,=Peneroplis (Spirolina) Li- 

 tuus, Gm. 



1808. Peneroplis lanatus, Alontf or t,= Peneroplis planatus, F. Sf M. 

 1826. Dendritina arbuscula, D' Or biyny, = Peneroplis (Dendrilina) 



arbuscula, D'Orb. 

 1839. Coscinospira Hemprichii, Ehrenberg, =Peneroplis (Spirolina) 



Hemprichii, Ehr. J 



' * See Ann. Nat. Hist. ser. 3. vol. viii. p. 235. Forskal describes this 

 species, and recognizes its marked variation of form, in ' Descript. Anim. 



*8 



