1894.] Schulze’s System of Descriptive Terms. 375 
The surface of the rostral end is “rostran” and the surface 
of the caudal end is “caudan.” The direction toward these 
are respectively “ rostrad” and “ caudad.” 
In a letter from Prof. Gage to Dr. Wilder which has been 
forwarded to me, the former very justly observes that “Schulze 
discards ‘ cephalic’ although he adopts caudal. Cephalic is 
certainly a more natural opposite of caudal than is rostral, the 
word he proposes in its place. Then cephalic has been and is 
used a great deal in English and considerably in German, and 
the use is increasing.” 
The main objection to this in my opinion, is that it applies 
to the vertebrata better than any other type and fails with the 
simplest forms of these. Among Ascidia, for example, there 
is perhaps a rostral extremity, but there is no caudal extrem- 
ity in the adults. There is an aboral region, but the oral 
region is central orcentran. While one therefore might make 
rostral, rostran and rostrad work well, some other term than 
caudal should be employed for the opposite pole. It seems 
contrary to all rational usage to employ terms having a defi- 
nite meaning like cephalic and caudal to bodies that have no 
head, nor representative oral opening, and no tail. 
Whenever in bilateral animals the mouth is at the extreme 
pole of the principal axis, I can see no objection to the use of 
oral, oran, orad, but when it is not there rostran, rostral and 
rostrad are highly appropriate. When the mouth is external 
and ventran, or lies out of the principal axis on any surface, 
as it is ina number of types, additional accuracy may possibly 
be given to the terminology if both rostral and oral planes or 
regions were recognized. At any rate this suggestion might 
be tested. 
Schulze uses “dorsal” and “ ventral” for the entire halves 
of the body respectively, the extreme surfaces are “ dorsan ” 
and “ventran,” the direction toward them “dorsad” and 
“ventrad.” The perlateral axis has “ dextral” and “sinstral” 
number of other terms synonymous with rostral and caudal, viz. atlantal and 
sacral, oral and aboral, proral and prymnal, actinal and abactinal were brought 
forward, even “Alpha ende” and “beta-ende” and the accompanying “alphal, 
alphan, alphad,” “betal, betan, betad” were proposed for the two ends of the 
Principal axis in bilateral animals. 
