16 



SHOULDER-GIRDLE AND BREAST-BONE. 



are very strong and ganoid ; the post-temporal (p. t.) is strongly attached to the occiput, has a 

 large ganoid surface, round behind, and oblique in front ; and under the oblique end is a strong 

 subcutaneous peg for articulation above. The supra-clavicle (s. cl.) is overlapped above by the 

 last ; it is leaf-like and carinate a little in front of the middle ; sinuous and notched behind its 

 blunt inverted apex, and hollow within (fig. I C). The clavicle (cl.) has a spatulate ganoid region 

 which is twice as large as an ordinary scale of this Pish ; but its subcutaneous part is very much 

 larger than the exposed part (figs. A and B, cl.), is like a strong curved nail with the head split, and 

 is strongly grooved within (fig. C). Above the hinder part of the head of the clavicle is the post- 

 clavicle (figs. A and C, p. cl.) ; it is a slightly modified ganoid plate, enamelled on the outside* 

 hollow within, notched above, and rounded below. The clavicle stands on the inner edge of 

 another large ganoid plate, a little behind its middle, this is the interclavicle (figs. A and B, i. cl.). 

 It is a most elegant plate, with three sides, the upper concave and sinuous ; the hinder transverse 

 and sinuous ; the lower or submesial straight and then notched (fig. B). This interclavicle has no 

 aponeurotic portion ; it is thin, marked with ridges of enamelled elevations that run parallel with 

 its outer superior margin, and it has its upper end (which lies a little behind and below the ena- 

 melled part of the clavicle) lobate. This plate and its fellow are the serial homologues of a pair 

 twice as large, that lie between the mandibular rami ; these beautiful lanceolate plates (fig. IB, ju.) 

 are the "jugulars" very characteristic of the Ganoidei, but occurring also in a few Clupeoid 

 Teleostei (in Meyalopssn&Elops, according to Cuvier), and, as I have recently found, they exist 

 likewise in the Lophobranchii. 



THE SHOULDER-PLATES OF CALAMOICHTHYS 



FIG. 1 C. 



p. cl. 



? gl- P- * p- & 2. 



p. 4.3. 

 (Magn. 10 diara.) 



(Magn. 5 cliam.) 



