304 
PALEONTOLOGY OF NEW YORK. 
vergent, slender jugal processes are given ofif not far from the origin of the 
lateral lamellae. The scars of the adductor muscles are situated just in front 
of the cardinal process on either side of the septum, and are not clearly 
delimited. 
Shell-substance highly punctated in all its parts. 
Type, Strophomena carinata, Conrad. Lower and middle Devonian. 
Observations. The original determination of the characters of Tropidoleptus 
led to its assignment with the terebratuloids. Presumably on account of its 
external expression, systematists and other students have generally been un¬ 
willing to admit this determination, placing the genus preferably among the 
strophomenoid and leptaenoid genera. After the examination of a large amount 
fig. 227. Fig. 228. 
Tropidoleptus carinatus, Conrad. 
Fig. 227. The interior of the bracliial valve; showing Ihe^cardinal process, crenulated dental sockets, loop and median 
septum. 
Fig. 228. The same in prolile; showing the height of the median septum and the mode of attachment of the lamellte of 
the loop. 
of material, representing the various growth-stages of the shell from a 
size less than 2 mm. in diameter to maturity, and having reviewed all 
the points involved in the original account of the brachidium, these have 
been found to be correct in every particular. In no observed condition 
of growth does there exist a deltidium on the pedicle-valve, and hence it 
becomes necessary to recognize Tropidoleptus as a terebratuloid genus, unique 
among the palmozoic brachiopoda. 
