MUSEUM OF COMPARATIVE ZOOLOGY. 83 



Androgynoceras * Hyatt. 

 The sides of the adult whorl slope outward and are ornamented with 

 pilte, usually single and set with two rows of tubercles. Abdomen narrow. 

 The large pila> of the young are split into smaller pilae on the abdomen of 

 the adult, but usually retain the characteristics of Microceras until a late 

 period of growth. The septa are more complicated than in Microceras, 

 and the increase by growth in the radii of the spiral is much greater, the 

 species consequently have fewer whorls- and are of larger size. The en- 

 velopment may cover up only the abdomen of each internal whorl, or ex- 

 tend over the whole side to the internal line of tubercles. 



Androgynoceras hybridum Hyatt. 



Amm. andror/i/noccras D'Orb.. Terr. Jurass., Ceph., p. 285, pi. 85. 

 Loc. Semur ; Coll. M. Boucault. 



Androgynoceras appressuni Hyatt. 



Loc. Rautenberg ; Coll. Dr. Krantz. 



This species is very much tlatter than Liparoceras Bechei, and differs also 

 in the development of the shell. The pilae^for a long time resemble those 

 of Microceras, the peculiar pilae of this genus are not brought out distinctly 

 until the fifth whorl is attained. 



Envelopment extends laterally to the internal line of tubercles. The 

 external tubercles are larger and more prominent than the internal row. 

 Abdominal lobe is deeper than the superior lateral, which last is deeper but 

 hardly broader than the inferior lateral. Lateral lobes and literal cells 

 unequally divided. 



Liparoceras t Hyatt. 



This genus differs from both of those previously described in the greater 

 breadth of the abdomen, the greater increase of the radii of the spiral, the 

 consequently smaller number of whorls, and the larger size of the species. 



The envelopment may cover only the abdomen of each internal whorl, 

 or extend to the inner row of tubercles. 



The pila? of the adult are split into numerous smaller pila?, and are orna- 

 mented on the sides with two rows of tubercles. The young are smooth on 

 the first two or three whorls, the pilffl never appear to assume, except to a 

 very slight degree, the characteristics of Microceras, but at once take on 

 the less prominent and diffuse character of L. Bechei. 



The septa also at an early period are more complicated than those of the 

 adult Microceras. The superior lateral cell is narrower proportionately 

 to the inferior lateral, than in the preceding genera. 



* AvSpuyvvos, hermaphrodite. f Anrapos, shining. 



