SPIROLOCULINA CANAL1CULATA. 109 



culata, as well as the less compact and weaker Sp. cymbium, and other forms 

 named by him at an earlier date, in 1826. 



If the exogenous shell-matter is strong at the sutures of the chambers, there 

 forming vertical lines or ridges on the two lateral surfaces or faces of the shell, 

 we have the Sp. dorsata, Reuss, Sp. limbata, Bornemann, S}). impressa, Terquem, 

 and some others ; but if the two marginal edges are widened out horizontally, the 

 shell has a canaliculate periphery. 



This characteristic marginal fluting seems to serve as a useful criterion ; and in 

 Part I, page 16, it was used as such, and Sp. canal icalata was chosen as the 

 subtype. The above list of synonyms excludes the forms that have square (plane) 

 margins ; but several of the varieties have some modification as well in this 

 respect as in sutural limbation, central concavity, and general outline. Indeed, 

 in our fig. 40 the marginal furrow is very feebly developed ; even stronger in 

 fig. 38. In the latter the planulate character predominates; in the former, as a 

 marginal channel is formed by limbation of its edges, the limbation of the sutures 

 is here of minor consideration. 



The following remarks on some canaliculate Spiroloculinse that have been 

 variously named will show how the minor features are modified, and how 

 complicated the nomenclature has become. 



(1) Spirolocttlina depressa, d'Orb, 1826 ('Ann. Sci. Nat.,' vol. vii, p. 298, 

 No. 1), according to Terquem, 1878 ('Mem. Soc. Geol. France,' ser. 3, vol. i, 

 art. 3, p. 54, pi. x, fig. 11, from d'Orbigny's unedited drawing, pi. i, fig. 1), is 

 canaliculate and limbate, hollow-chambered, and slightly excavate (not Williamson's 

 fig. 177, which has an angulate margin); but the Model No. 92 having been 

 taken for the type and criterion in 1865 and 1871, it is best to adhere to the 

 conclusion then arrived at of its being planulata. 



(2) Spirolocttlina perforata, d'Orb., 1826 ('Ann. Sci. Nat.,' vol. vii, p. 298, 

 No. 2 ("Modeles, No. 92," is a misprint)), according to Terquem, 1882 ('Mem. 

 Soc. Geol. France,' ser. 3, vol. ii, art. 3, p. 154, pi. xxiv, figs. 3 and 4 (? Ophthal- 

 midium), after d'Orbigny's unedited drawing, pi. i, fig. 2), is canaliculate, limbate, 

 excavate, and narrow. 



(3) Spirolocttlina Grateloupi, d'Orb., 1826 ('Ann. Sci. Nat.,' vol. vii, p. 298, 

 No. 3), according to Terquem, 1878 ('Mem. Soc. Geol. France,' ser. 3, vol, i, 

 art. 3, p. 52, pi. x, fig. 5 ; and var. fig. 6, after d'Orbigny's unedited drawings, 

 pi. i, figs. 9 — 11 ; and in ' Mem. Soc. Geol. France,' ser. 3, vol. ii, art. 3, p. 155, 

 pi. xxiv, fig. 6), is broadly channelled on margin (canaliculate) and limbate. 



