Figure H.—Parahollardia lineata: with 

 dots representing the course of the inconspicuous 

 lateral line; lower left, scales from upper middle 

 region of body, including two lateral line canal 

 bearing scales; lower right, nasal region as seen 

 externally (above) and the olfactory lamellae as 

 seen with the top of the nasal sac removed. 



with the exoccipitals, anterolaterally with the prootics, 

 and, with sHght interdigitation, anteroventrally with the 

 overlying posterior end of the parasphenoid. The rim of 

 the round concave posterior end of the basioccipital ar- 

 ticulates by fibrous tissue with the rim of the concave an- 

 terior face of the centrum of the first vertebra. A deeply 

 concave medial channel is present on the anterior half of 

 the ventral surface of the basioccipital, but the channel 

 is mostly hidden from view by the overlying para- 

 sphenoid. Posteriorly this channel is open to the exterior 

 at the base of the posterior bifurcation of the para- 

 sphenoid, while anteriorly it opens into the myodome 

 where the anterior end of the basioccipital forms the 

 posterodorsal and posterolateral walls of the myodome. 



Exoccipital. — Cartilage filled at its dorsal, lateral, 

 and ventral edges; articulates through cartilage dorsally 

 with the epiotic, anteroventrally with the prootic, ventro- 

 medially with the basioccipital; articulates laterally 

 through cartilage and slight interdigitation with the 

 overlying pterotic. Medially the exoccipital forms the 

 lateral and ventral walls of the foramen magnum, the 

 foramen being closed dorsally by the cartilage between 

 the dorsomedial edges of the two exoccipitals. Postero- 

 medially the exoccipitals are firmly attached by fibrous 

 tissue and slight interdigitation to the anterior surface of 

 the elongate, laterally expanded, bifid neural spine of the 

 first vertebra. The exoccipital condyle is a short pos- 

 terior prolongation of the posterior edge of the bone just 



above its articulation with the basioccipital, forming a 

 plate which overlies the lower anterolateral surface of the 

 neural arch of the first vertebra just above the region of 

 the centrum. 



Supraoccipital. — Dome-shaped, its stout rounded 

 anterodorsal edge forming the apex of the cranium and 

 its posterior surface convex; cartilage filled along all of 

 its ventral edges; articulates posteroventrally through 

 cartilage with the epiotics and anteroventrally through 

 cartilage and slight interdigitation with the overlying 

 frontals. 



Otic Region. 



Pterotic. — Cartilage filled along all of its edges of 

 articulation with the other cranial bones; articulates 

 posterodorsally through cartilage and extensive inter- 

 digitation with the epiotic, posteroventrally through car- 

 tilage and slight interdigitation with the exoccipital, 

 anterodorsally through cartilage with the sphenotic, and 

 anteroventrally through cartilage with the prootic. Along 

 the middle of the anterior half of its ventral surface the 

 pterotic articulates with the hyomandibular through 

 fibrous tissue, the articulation being somewhat flexible. 

 Posterolaterally the pterotic is broadly overlain by the 

 posttemporal to which it is firmly interdigitated. 



Sphenotic. —Cartilage filled along all of its edges of 

 articulation with the other cranial bones; articulates 

 through cartilage posterodorsally with the epiotic, 

 posteroventrally with the slightly overlying pterotic, ven- 

 tromedially with the prootic and dorsomedially with the 

 pterosphenoid. Dorsally the sphenotic is broadly over- 

 lain by and slightly interdigitated with the frontal. On its 

 ventral surface the medial edge of the sphenotic ar- 

 ticulates by fibrous tissue with the hyomandibular. 



Epiotic. — Cartilage filled along all of its edges of 

 articulation with the other cranial bones; articulates 

 through cartilage dorsally with the supraoccipital, 

 anterodorsally with the occasionally slightly overlying 

 frontal, anteriorly with the sphenotic, and posteroven- 

 trally with the exoccipital. Ventrolaterally the epiotic ar- 

 ticulates anteriorly through cartilage with the pterotic, 

 but more posteriorly the pterotic broadly overlies and in- 

 terdigitates with the epiotic. Along the lower portion of 

 its posteromedial edge the epiotic bends anteriorly so 

 that a shallow, vertical depression or groove is formed 

 where the two epiotics articulate through cartilage with 

 one another medially. The ventral end of the stout shaft 

 of the first basal pterygiophore of the spiny dorsal fin fits 

 into this depressed area and is held tightly to it by 

 fibrous tissue. This depression in the back of the skull is 

 continued ventrally by a similar intuming of the upper 

 third of the medial edges of the exoccipitals. 



Prootic. — Cartilage filled along all of its edges of 

 articulation with the other cranial bones, except an- 

 teriorly; articulates through cartilage anterodorsally with 



