— 173 — 



larger than the other organs of the line, and may perhaps represent the two organs usually found 

 one in this bone and the other in the supraelavicular in the other fishes of the group. 



On the ventral surface of the bone there is a stout V-shaped flange, projecting ventro-antero- 

 mesially. The Hne of origin of the anterior limb of the V begins at the rounded antero-mesial conier 

 of the bone, and from there runs postero-laterally until it reaches the angle between the mesial and 

 lateral portions of the bone. There it turns postero-mesially, nearly at a right angle, and so continues 

 until it reaches the mesial edge of the bone at about its middle point. From this right-angled line 

 of origin, the V-shaped flange projects ventro-antero-mesially, its two limbs and the overlying 

 body of the bone enclosing a sub-pyramidal space which forms the lateral, recess-like corner of the 

 large fossa on the bind end of the corresponding half of the skull. The angle of the V-shaped flange 

 is thickened. and its ventral end suturates with the exoccipital, the dorsal portion of the mesial edge 

 of the anterior limb of the flange suturating with the postero-lateral end of that flange on the internal 

 surface of the epiotic that represents the posterior surface of that bone. At the dorso-mesial corner 

 of the anterior surface of the anterior limb of the flange on the suprascapular, there is a small recess 

 which lodges but is not in synchondrosis with the bind end of the band of cartilage that lies between 

 the pterotic and exoccipital. The mesial edge of the suprascapular here closely approaches the lateral 

 edge of the dorsal plate of the epiotic, but apparently does not touch that bone. The V-shaped flange 

 of the suprascapular must accordingly certainly contain the opisthotic process of the bone, and it 

 probably represents both that process and the epiotic process, joined by a web of bone which entirely 

 closes the space usually occupied by the posterior opening of the temporal fossa. However this may 

 be, a posterior opening of a temporal fossa is whoUy wanting in this fish, and if any portion of the 

 fossa exists it must open on the lateral surface of the skull and hence be represented in the posterior 

 portion of the large subtemporal fossa. In certain specimens of Cottus octodecimospinosus, I have 

 already shown that the posterior opening of the temporal fossa may be entirely closed by the invading 

 growth of its bounding bones, the fossa then opening wholly on the lateral surface of the skull. In 

 such a fish, if the subtemporal fossa were to be greatly deepened, as it is in Dactylopterus, it would 

 inevitably absorb and incorporate in itself a posterior portion of the adjoining temporal fossa. But 

 in that case the epiotic should form part of the bounding wall of the fossa, and I can not find that 

 it does so in Dactylopterus; the epiotic here apparently being everywhere covered by the bind end 

 of the pterotic-exoccipital band of cartilage which lies in the bottom (roof) of the fossa. The lateral 

 edge of the epiotic, immediately anterior to the pedicle of the suprascapular, comes close to the 

 lateral edge of the pterotic-exoccipital cartilage and may there perhaps be exposed, thus forming 

 part of the bounding wall of the subtemporal fossa. Furthermore, the subtemporal fossa, as defined 

 by Sagemehl, is said to be an excavation of the cranial wall within the arch of the external semi- 

 circular canal, but, in Dactylopterus, the fossa has a large portion which lies posterior to that canal. 

 This posterior extension may therefore represent the posterior portion of the temporal fossa of the 

 fish, here incorporated in the subtemporal fossa by the unusual development of the latter. 



On the ventral surface of the suprascapular, close against or even cutting into the lateral edge 

 of the base of the posterior limb of the V-shaped pedicle, there is a deep circular pit, so deep that it 

 shows, on the dorsal surface of the prepared skull, as a circular translucent spot in the bone. This 

 pit gives origin to strong fibrous tissues which have their Insertion on the dorsal end of the clavicle, 

 that end of the clavicle not apparently entering the pit, in prepared specimens, but the pit being 

 quite certainly developed in articular relation to it. At the anterior margin of the pit there is a slight 



