Ill* The American Geologi8t, August, 189$ 
septa of adjacent corallites at their outer margins, bearing 
numerous, thin, lamella-like carina' on their sides in the region 
outside the central pit, very finely denticulated on their 
Tree margins, divided into two orders that occiii- alternately. 
those of the first order extending into the central area where 
they are non-carinated and are usually twisted together to 
form a pseudo columella; the septa of the second order end 
abruptly at the margin of the central area. Diaphragms 
limited to a very narrow central area. Dissepiments feebly 
developed in the interlocular spaces. 
Near the outer margin of the corallites the septa and carina? 
become somewhat confused, the septa are often sinuous or 
zigzag, and the carina' complicated by the presence of addi- 
tional elements, to the simple ridge of which a carina is 
usually constituted. The extreme of confusion and compli- 
cation occurs where adjacent corallites blend into each other. 
In polished specimens the central area seems to be quite defi- 
nitely set off from the outer. This appearance is due to the 
absence of carina' within the central area, the suppression of 
each alternate septina at its margin, and the crowded condition 
of the carina- and dissepiments just outside the central pit. 
The species in question is in no way related to Strombodes 
and cannot ever be compared with Astrea .' gigas (Strombodes 
gigas)of Owen. 
THE PROTOCONCH OF ORTHOCERAS. 
By J. M. Clarke. 
Divergent views in regard to the nature of the protoconch 
in the nautiloid genus, Orthoceras, have been expressed by 
Professor Hyatt and Dr. Branco, the principal investigators 
of the developmental phases of this genus. The facts re- 
corded by both these eminent observers art', in the main, the 
same. 
Branco has considered as the embryonal shell or protoconch 
("Anfangskammer"), the conical or cup-shaped termination 
of the tube as usually found, and which generally bears upon 
its outer and distal surface a "Narbe" or cicatrix. This 
chamber is separated from the second in order by a siphonated 
septum, the suture of which is not deeply impressed, or its 
place indicated on the exterior of the tube by a groove or con- 
