SYSTEMATIC ZOOLOGY—GILL. 453 
called the thirteenth), corrected this error, and returned all the 
Nantes to the class of Pisces, thus reverting to the older view of Linné 
himself. The Pisces of Linné included only the genera left after the 
exclusion of those just named and also of Myxine, which last was 
referred to the class of Vermes between the leeches (Hirudo) and the 
shipworms (Zeredo). 
LINNEAN GENERA. 
The genera of Linné were intended and thought by him to be natu- 
ral,* and natural groups some of the so-called genera were, but pres- 
ent opinion assigns to most of them a very different valuation from 
that given in the “ System Nature.” Some of the genera of Inverte- 
brates were extremely comprehensive. For example, Asterias in- 
cluded all the members of the modern classes of Stelleroidea or Aste- 
roidea and Ophiuroidea; /’chinus was coequal with the Echinoidea ; 
Cancer, Scorpio, Aranea, Scolopendra, and Julus were essentially co- 
extensive with orders or even higher groups of the zoologists of the 
present time. Others were so heterogeneous that they can not be com- 
pared with modern groups. Thus /olothuria, in the last edition of 
the “ Systema,” was made to include four holothurians in the modern 
sense, a worm, a physaliid, and three tunicates; in other terms, the 
so-called genus included representatives of four different classes and 
even branches of the animal kingdom. 
It has been stated by various writers that the genera of Linné were 
essentially coequal with the families of modern authors, but, as has 
been indicated, such is by no means the case. Other striking excep- 
tions to the generalization may be shown. 
Not a few of the genera of Vertebrates, although not of the super- 
lative rank as several of the Invertebrates, were equivalent to orders 
of modern zoology; such were, in the main, Simia, Testudo, Vesper- 
tilio, and Rana. Simia included all the anthropoid Primates except 
man; Vespertilio was equivalent to the order Chiroptera less the 
genus Noctilio; Testudo was exactly equal to the order Testudinata or 
Chelonia; Rana to the order Salientia or Anura. A number of other 
genera of one or few species known to Linné were also of ordinal or 
subordinal value. 
In striking contrast with the range of variation of such genera 
were others, of which several, well represented in northern waters, 
may be taken as examples. Scorpwna was distinguished simply be- 
cause it had skinny tags on the head;’ Zabrus because it had free 
membranous extensions behind the dorsal spines;° and Cobztis be- 
@Classis et ordo est sapientie, genus et species Naturze opus.—Linn. Syst. 
INEM SG ely 
+ Scorpena. Caput cirris adspersum. 
¢Labrus, Pinna dorsalis ramento post spinas notata, 
