GASTEEOPODA. 13 



Ammonites Libanensis? Conrad. 



Ammonites Libanensis Conrad, 1852, OfBci;il Report, p. 234, App., PI. vi, fig. 46. 



Fragment of the cast of an outer whorl, apparently fi'om the upper po.s- 

 terior portion of an individual of the species above named. Width of whorl, 

 60nnn.; thickness, 63 mm. Measured along the dorsal surface, the fragment 

 has a length of 70 una. It bears nine transverse ribs, little prominent and 

 about as wide as tlie interspaces. 



The specimen is too small a part of the whole fossil, and too imperfectly 

 preserved, to admit of positive identification. Coll. Merrill. 



Locality and Positluu. — Beirut district ; probably from the same horizon 

 as the last two species. 



GASTEROPODA. 



Of the species enumerated under this title, those designated as being 

 from the Bird collection are from Abeih, or its vicinity, and agree in their 

 rock material with tlic beds of Fraas's Gaderopod zone of Ahcih, the lowest of 

 six members which, according to his view, make up the Turonian stage of 

 the Cretaceous of that region. At Chan Shanuir, near Abeih, a natural 

 profile shows the zone to have seven subdivisions, of which there need be 

 mentioned here only the lowest, a thick bed of red and yellow ferruginous 

 sandstone, and two thinner and higher beds of yellow marl. The latter rock 

 is spoken of as especially exposed at Abeih, and as yielding, through weath- 

 ering, the well-preserved Gasteropods for which that locality is famous above 

 all others of the region. Fraas's language implies, but does not definitely 

 assert, that the marl only is productive of recognizable species. Our speci- 

 mens show this marl to be for the most part soft and earthy, with inter- 

 mingled bits of broken shells; but the rock material as.sociated with our 

 finest univalves from Abeih is arenaceous, couiposed indeed of calcareous — 

 not siliceous — grains, and, like the earthy marl, ferruginous and mingled 

 with the dcbrh of shells. Were the sandstone above mentioned known by 

 us to be friable and to furnish well-preserved shells, we sliould suppose the 

 species in question to be from that portion of the zone. But in the absence of 

 proof that the sandstone is thus prolific, we must I'cgard them as coming prob- 

 ably from an arenaceous portion of the marl, and shall so refer to them. 



