On the Ascoceratidce and Lituitidce. 379 



criticized. The author claims to be the first to have seen the 

 " Nautiloid " portion of Ascoceras, and we think justly; for the 

 specimen found in 1877 by Barrande (Syst. Sil. de la Boheme, 

 vol. ii. Suppl. p. 98, pi. ccccxci.) with two septa beneath the first 

 sigmoid one, regarded by him as deciduous septa, are, in fact, says 

 Lindstrom, " the first two septa of the Ascoceras, and the lowermost 

 of these is the truncated extremity." 



The following (thirteen) new species of Ascoceras are described 

 (pp. 20 — 33) and figured : — cochlea turn, dolitim, fistula, pupa, reticu- 

 latum. manubrium, ampulla, collare, lagena, cucumis, deripievs, sipho, 

 gradatum. Besides these, A. Bohemicum, Barrande, is described and 

 figured. Passing over Glossoceras and Billingsites, about which the 

 author has nothing special to remark, we come to the new genus 

 Choanoceras 1 (Figs. G, h) described as having a shell "resembling a 

 faintly -curved Orthoceratite, with the lower extremity truncated and 

 conically pointed." The aperture is probably simple; the body- 

 chamber very large, occupying almost nine-tenths of the whole shell. 

 Septa from four to six, formed like a pointed, oblique funnel. All 

 the septa are equally well developed in young specimens, but in the 

 adult, in which there are six septa, three of these are complete, 

 and the three earlier ones incomplete or lacunose. The siphuncle is 

 nummuloid in the older individuals, cylindrical in the younger, and 

 the necks of the septa hook-like and strongly recurved. This genus 

 contrasts with Ascoceras in the meagre development of its lacunose 

 septa. The position of the latter may also be contrary to those in 

 Ascoceras, supposing that the convex side of the shell is the ventral, 

 and the concave the dorsal, as is assumed in Ascoceras. In Choano- 

 ceras the lacunose part of the septa is placed against the convex side; 

 in Ascoceras near the concave side. One species of Choanoceras is 

 described and figured, viz. C. mutabile. 



A fragment of an unknown genus is figured by Dr. Lindstrom, 

 who describes it as having "pointed and funnel-like septa; but 

 regularly placed in the median axis of the straight shell." The 

 necks of the septa are very long and continuous down to the bottom 

 of the next septum, " thus forming, as it seems, the entire siphuncle." 

 It cannot, therefore, belong to the present group. 



Under the Lituitidse, two species of Ophidioceras are described 

 and figured, viz. 0. reticulatum, Angelin, and 0. rota, sp. nov. Of 

 this genus Dr. Lindstrom observes that there is nothing to add to the 

 generic characters given by previous authors, except that the body- 

 chamber is of extreme length in all the Gotland specimens that have 

 been sectioned. It occupies, namely, more than one whorl, and some- 

 times more than two. 



Referring to the classification of the Ascoceratidee and kindred 

 groups, Dr. Lindstrom dissents from Hyatt's allocation of his 

 (Hyatt's) genus Billingsites with Mesoceras, Barr., in the family 

 Mesoceratidge (Hyatt). Dr. Lindstrom considers that Billingsites 

 should be " placed amongst the Ascoceratidge near Glossoceras on 

 account of its contracted aperture, while Ophidioceras may keep 

 1 From xifaws a funnel. 



