34 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 
cus); a form from the Eifel Devonian, described below as D. pelmensis ; 
Pelecyphorus Trantschold ; Asterolepis bohemica Barrande (hereinafter 
described as D. bohemicus); Dinichthys; and lastly, the genus Titan- 
ichthys, which is so closely allied to Dinichthys as to pass for a mutation 
or modification of the same. Titanichthys is, essentially, a huge Dinich- 
thys with lighter bones and a degenerate dentition. It is presumable 
that when the osteology of Brontichthys, Gorgonichthys, Mylostoma, 
Trachosteus, and related genera, shall have become known as fully as in 
Dinichthys, their affinities with one another will be found to be much 
closer than with the more primitive Coccosteids. Newberry was in- 
clined to regard these forms as constituting a distinct family, the Di- 
nichthyide ; but that would rather overreach the mark. We venture to 
adopt the middle course, and assign to the forms enumerated above the 
rank of a subfamily, known as the Dinichthyine. 
As already remarked, we may regard the presence of a carinal process 
as sufficient ground for referring detached dorso-median plates to the 
Dinichthyine, instead of the Coccosteide in general. For precise gen- 
eric determination, a knowledge of the dentition is of course necessary ; 
but where we are in ignorance of the dentition, we may conveniently 
place all species founded upon such dorsal shields, for the time being at 
least, under the single genus Dinichthys. Precedent. for this is already 
furnished by D. precursor, D. ringuebergi, D. tuberculatus, and the plates 
from the Genesee Shale referred to above as D. (1) minor. To this 
category may now be added the following new species: D. livonicus, 
D. trautscholdi, D. pelmensis, and D. pustulosus. 
Dinichthys livonicus nomen nov. 
1857. Coccosteus aus Livland, ©. H. Pander, Ueber die Placodermen des devon- 
ischen Systems, p. 70, Plate B, Fig. 4, 
1889. Coccosteus, H. Trautschold, Ueber Coccosteus megalopteryx, etc. (Zeitschr. 
deutsch. geol. Gesellsch., Vol. XLI. p. 38). 
1896. Dinichthys livonicus, ©. R. Eastman, Observations on the Dorsal Shields 
in the Dinichthyids (Amer. Geol., Vol. XVII. p. 222). 
The original of Pander’s Plate B, Fig. 4, of his Placodermen des devonischen 
Systems, may be taken as the type of this species, and there may be presum- 
ably associated with it the specimen referred to by A. 5. Woodward (Brit. 
Mus. Cat. No. P. 4731), in his Catalogue of Fossil Fishes, Vol. II. p. 293. 
‘Without doubt this represents one of the smallest and most primitive species 
of Dinichthys, yet its marked development of the carinal process in proportion 
to its size is sufficient reason for excluding it from Coccosteus. It apparently 
