226 
AUG. F. FOERSTE 
25. LOXOCERAS McCOY 
PLATE XXVIII, FIGS. 2A, B 
Selected genotype: Loxoceras distans McCoy 
The genus Loxoceras was defined by McCoy as consisting of 
orthoceracones “in which the section is oval, the septa waved and 
placed obliquely with respect to the axis of the shell, and the si- 
phuncle is excentric.'' This description is accompanied by a 
figure,®'^ in which the sinuosity of the sutures of the septa agrees 
with that of Loxoceras distans McCoy, though the septa are 
drawn closer together. A study of the figures presented by Mc- 
Coy in connection with his generic descriptions, in the volume 
cited, suggests that these figures were intended to be diagram- 
matic, and not accurate representations of type specimens. 
Moreover, he certainly never intended the first species described 
in the text under this generic name to be accepted as the type. 
Had he done so, he would not have published Orthoceras hreynii 
Martin (Plate XXV, Fig. 3) first, but would have selected the 
one he published second, namely Loxoceras distans McCoy, which 
differs from the figure accompanying the original description of 
the genus chiefly in having more distant septa. The sutures of 
Orthoceras hreynii present undulations, but of moderate obliquity 
compared with typical Loxoceras, and the siphuncle is located 
near the middle of that broad side of the conch along which the 
sutures curve moderately downward. 
In Loxoceras distans, on the contrary, the sutures of the septa 
are strongly oblique in a sigmoid direction, and the location of 
the siphuncle is central. The word Loxoceras means oblique 
horn, and evidently refers to the strongly oblique sutures. 
The siphuncle of Orthoceras hreynii Martin is described by 
McCoy as follows : 
“Siphuncle small, and a little within the margin, where it 
passes through the septa, but dilated between them into de- 
pressed spheroidal beads, about twice as wide as long, and touch- 
ing the surface throughout the length of the shell; interior of 
the siphon traversed by a small continuous tube, attached to the 
inner walls of the dilated portion by radiating, vertical, shelly 
partitions (about eight in a whorl) ,• constricted by transverse 
stronger partitions in the middle of each dilation (or intermediate 
between the septa) . Surface, (of the shell) indistinct, apparently 
marked with fine, obtuse, transverse striae. The proportion of 
“ McCoy, Syn. Carb. Foss. Ireland, 1844, p. 6, fig. 3. 
