DEVELOPMENT OE THE SKULL IN THE SALMON. 
07 
pterygoid (the Owenian name in this case, and answering to the internal “pterygoid” 
of Cuvier) does not answer to the internal pterygoid plate of Man and the other Mam- 
malia, but to an additional bone occasionally seen even in them. By adopting the term 
“ transpalatine ” for the Reptilian transverse bone, “ pterygoid ” for the homologue 
of our internal pterygoid plate, and “ mesopterygoid ” for the innermost or submesial 
plate, I seem to myself to have struggled out of a quagmire of obstructive terms on to 
something like a raised causeway. 
Many specially ichthyotomical terms must be retained, such as “ hyomandibular,” 
“ symplectic,” and the like ; for although we now begin to see what the representatives 
of these bars are transformed into in the higher classes, yet they have in their more 
primitive condition in the Fish an essentially specific character as morphological elements; 
whilst their metamorphosed counterparts in the higher types may be compared to new 
species, developed during secular periods. 
In my last paper I stated my opinion as to the merely varietal value of the bony 
deposits that take place in the general connective web ; these bony plates may be 
superficial , intermediate , or deep, the latter mostly fastening themselves on to carti- 
laginous tracts, and causing their transformation into true bone. 
We have three groups of such bones — namely, “ dennostoses,” “parostoses,” and 
ectostoses in the Teleostei, as a rule, there are no “ endosteal ” deposits, or direct 
calcification of cartilage-cells, such as we see in Sharks, Rays, and in the “ Anoura in 
the Salmon there are no “ dennostoses ” nor “ endostoses.” 
If the reader will refer to the figures of Callichthys (a Teleostean covered with Ganoid 
armour) in my memoir ‘ On the Shoulder-girdle,’ he will see how gently and almost 
insensibly the body-plates pass into the armour for the head ; this is the first degree of 
specialization in relation to the cephalic endoskeleton. A further degree is obtained 
by the ossific deposit being found in a deeper stratum, the skin itself becoming the seat 
of deposits that form the proper scales of the fish, unrelated to the cartilage beneath ; 
this we see in most Teleostei. 
Let this be held in mind, and then all those bony plates in the Salmon’s head which 
do not engraft themselves upon the cartilaginous skull and face can be arranged into 
one category — the splints, or “ parostoses.” 
The deeper strata of bony deposit, on account of their peculiar behaviour correlative 
to the endoskeleton as “ ectosteal ” laminae, are, as it were, taken into the very body and 
substance of the endoskeleton, and become part and parcel of it ; they may be called 
secondary endoskeletal elements , in contradistinction to the parts into which they grow, 
which are primary. 
Thus in morphological species, as well as zoological, there is frequently a dovetailing 
of members, a mutual trespassing of territories; and the sharp boundaries, which for 
the sake of logical clearness we are always drawing out, often belong to us, as intellectual 
conceptions, rather than to Nature, as solid and tangible facts. 
Before concluding these remarks I must express my gratitude to Dr. Traquair for 
