86 AMMONITID^, 



incomplete Ancylocerse. H. cristatus, d'Orb. (xxxii, 29). Grault; 

 Soiitliern France. 



TuRRiLiTES, Lam., 1801. 



Etyra. — Turris, a tower, lithos, a stone. 



Distr. — 37 sp. Gault to Chalk ; Europe. T. costatiis, d'Orb. 

 (xxxiii, 31). T. Boblayi, d'Orb. (xxxiii, 38). 



Shell spiral, depressed to elongate, sinistral ; sutures six-lobed, 

 foliated ; aperture often irregular. 



The animal of Turrilites was perhaps dibranchiate by the 

 atrophy of the respiratory organs of one side. 



HETEROCERAS, d'Orb., 1847. Shell like Turrilites, but last 

 chamber somewhat produced and recurved. 5 sp. Cretaceous ; 

 Europe, United States. T. Emericii, d'Orb. (xxxiii, 39). 



HELicANCYLOCERAS, Gabb, 1869. Spire less elevated, volutions 

 less decidedly in contact. 



HELTCOCERAS, d'Orb., 1842. (Helix [helicos'], a spiral, ceras, 

 a horn.) Shell spiral, sinistral; whorls separate ; annular costse 

 passing uninterruptedly over the siphonal side. 1 1 sp. Inferior 

 Oolitic (?) to Cretaceous ; Europe, India, United States. 



PATOCERAS, Meek, 1876. Costee interrupted on the siphonal 

 side, leaving a narrow, smooth space along the whole length of 

 the same. T. Teilleuwii, d'Orb. (xxxiii, 36). Jurassic. 



Baculitbs, Lam., 1801. 



Etym. — Bacillus, a staff. Syn. — Cyclomera, Conrad, 1866. 



JJistr. — 20 sp. Cretaceous ; Europe, Chili, India, United 

 States. B. anceps, Lam. (xxxii, 30). France. B. baculoides, 

 d'Orb. (xxxii, 31). * 



Shell straight, elongated, conical ; suture foliately lobed ; last 

 chamber large ; margin of aperture dorsally produced. 



The baculite limestone of l^ormandy is so called from the 

 numerous remains of the shells of this animal which it contains. 



Conrad has given the name Cycloceras to a Baculite figured 

 b}^ him, but without generic characters ; afterwards, finding that 

 jiame preoccupied by M'Coy, he changed it to Cyclomera, still 

 giving no diagnosis. 



Meek divides Baculites into two subgeneric forms, which, he 

 remarks, are possibly distinct genera. 



BACULITES, Lam. (typical), a. Shell straight throughout ; 

 aperture directed forward ; lip with lateral sinuses directed back- 

 ward ; the projection of its siphonal margin, straight, and its anti- 

 siphonal margin convex in outline ; interior without regularly 

 disposed ridges. B. vertebralis, Lam. 



(?) b. Shell straight posteriorly, but with the non-septate part 

 gently arcuate ; aperture a little oblique ; appendage of siphonal 

 side of lip arching slightly with the general curvature of the non- 



