35 
Genus BACILLUS Cohn, 1872. 
[Not Bacillus Latreille, 1825, orthopteron.] 
This genus was proposed b}" Cohn as a genus of plants, namely, after 
the bacteria had been eliminated from zoology; accordingly the name 
is not influenced by the existence of Bacillus Latreille, 1825. If, 
however, later investigations should again transfer this genus to the 
animals, the name Bacillus Cohn should be rejected by zoologists 
because of Bacillus Latreille, 1825. 
Cohn's genus originally contained three species, as follows: 
1. Bacillus subtilis (Ehrenberg, 1833) Cohn, 1872; Cohn records Vibrio subtilis 
Ehrenberg as synonym. 
2. Bacillus anthracis Cohn, 1872; not examined by Cohn. To Bacterium by later 
authors. 
3. Bacillus ulna Cohn, 1872; retained in Bacillus by Migula. 
Cohn (1872, 178) mentions Vibrio bacillus in his discussion of 
Bacillus , but it is not clear that he definitely includes V. bacillus in 
the genus. This does not, therefore, appear to be a clear case of type 
by absolute tautonymy. If this case were ruled upon by page prece- 
dence, Bacillus subtilis would be the type. If preference were shown 
to the medicinal species (Linntean rule) Bacillus anthracis would be 
taken as type. This ruling is, however, contraindicated by two fac- 
tors, namely: B. anthracis was not examined b} T Cohn, and it has been 
eliminated from Bacillus . It would be better to take a species 
examined by Cohn and one not since eliminated. Were I ruling on 
this case as a zoological genus, I should accept B. subtilis as t} T pe of 
Bacillus. 
Art. 31. The division of a species into two or more restricted 
species is subject to the same rules as the division of a genus. But a 
specific name which undoubted^ rests upon an error of identification 
can not be retained for the misdetermined species even if the species 
in question are afterwards placed in different genera. Example: 
Taenia pectinata Goeze, 1782= Cittotaenia pectinata (Goeze), but the 
species erroneously determined by Zeder, 1800, as “ Taenia pectinata 
Qoeze'' =Andry a rhopalocep>hala (Riehm); the latter species does not 
take the name Andrya pectinata (Zeder). 
Discussion.— The species Taenia solium , 1758, included both T. 
solium and T. saginata of the present day. Bloch (1782a) definitely 
cited T. solium as an armed species; Goeze (1782a) showed that two 
forms were present, but he fell into error in renaming both species; 
again the two species were confused, but Virey (1823) named Penta- 
stoma coarctata (which corresponds to the unarmed species) as a new 
form; later authors confined T. solium to the armed species. The 
history of the species calls for the retention of T. solium for one of 
the species, and the name has been quite generally applied to the 
