64 CEPHALOPODA. 



Pale sulphur-yellow ; very fragile, horn-shaped ; diameter about 

 one inch. Inhabits the West Indian seas. 



Peron has ascertained that this shell is attached at the lower part of the 

 animal to which it belongs, and that it is completely enveloped by its body, 

 except a portion of its last spiral volution. 



FAMILY VII. ORTHOCERATA. 



Shell straight, or nearly so, without any spiral volutions. 



Genus 29.— C O NILI TE S.— Lamarck. 



Generic. Character — Shell conical, straight, slightly inflected ; 

 outer crust thin, by which the nucleus is invested ; nucleus some, 

 what separable, multilocular, and divided by transverse septa. 



Conilites pyramidata. — The Pyramidal Conilites. Plate 

 X. fig. 25. Pyramidal ; with the concave bands contracted. 

 Fossil. 



Genus 20 — HIPPURITES.— Zonjarc/i. 



Generic Character. — Shell conical-cylindrical, straight, or 

 somewhat arcuated, multilocular, with transverse septa ; having 

 a lateral internal channel formed by two parallel, longitudinal, 

 and obtuse ridges ; the last chamber closed by an operculum. 



Hippurites curvo. — The Bent Hippurites. Plate X. fig. 

 26. Conical, curved, rough ; lower part truncated and flat. 



Genus 31 — l^OD OS ARIA.— Lamarck. 



Generic Character. — Shell elongated, erect, or smooth, and 

 slightly arcuated, subconic, nodose, consisting of a series of 

 spherical volutions ; the transverse septa perforated. 



Nodosaria radicula. — The Shining Nodosaria. Plate X.' 

 fig. 27. Erect, oblong, and attenuated ; with five globular vo- 

 lutions. Two lines long. Inhabits the Adriatic. 



Genus 32.— ORTHOCERA.— ZawarcL 



Generic Character. — Shell elongated, straight, or a little arcu- 

 ated, subconical ; ribbed, with longitudinal, external grooves ; 

 chambers formed by transverse septa, perforated by a tube, 

 which is either central or marginal. 

 The shells of this genus resemble a slightly curved horn. 



