35 301 



Orbitals of Siphonostoma, and other Syngnatliids is in accord with the fact that all 

 the other hones of the skull as well as the dermal plates of the body are devoid of 

 canals; and besides, if infraorbitals are found in other members of the group "So- 

 lenichthges" (which is the case with Amphisile, Centriscus, Aulostoma) they also lack 

 canals. 



hi Siphonosloma, and the Syngnathids generally, the connection between the 

 cranial beak and the suspensory bones appears to be somewhat looser or weaker 

 than in the preceding genera. 



The hyoid (PI. VI, figs. 1, 4, 5) is short, reaching only about to the front end 

 of the first gill arch; it is composed of but 4 pieces, no division between an epi- 

 hyal and a ceratoliyal being visible. If we compare this form with Aulostoma and 

 Fistnlaria it seems possible that the ceratohyal has vanished , or has been fused 

 with the large lower hypohyal (by'); but I have not been able to lind any trace 

 of a suture, neither in the hypohyal nor in the epihyal, which might indicate two 

 constituents. The lower hypohyal is very large as in the other members of the 

 "So/eHic/i//i£/es", and also here a considerable part of it covers the inside (fig. 4) of 

 the epihyal (eh), whereas the latter overlaps on the outer side (fig. 5). The upper 

 hypohyal (by") is very small, roundish; the stylohyal (st) short and stout, with the 

 articular head facing outwards, and carrying on the inner side, below the articular 

 head, a strong process, which is connected by ligament with the syniplectic. The 

 epihyal on its outer side has a strong, triangular process, and below this are fixed 

 the two long and slender branchiostegals (r), the upper of which is the stouter; 

 both follow the opercular margins to the small gill-slit close to the nape (PI. V, 

 fig. 5 r). 



The glossohyal (PI. VI, figs. 1, 10 gl) is long and slender; the foremost longer 

 part is cartilaginous; the proximal osseous part hardly projects over the anterior 

 end of the hyoid; behind it is closed, without cartilage (sometimes a small separate 

 nodule of cartilage is found between it and the first basibranchial). The urohyal 

 is fairly long, reaching backwards past the level of the articulation of the hyoid; 

 in front it is broad, head-shaped, the remaining part laterally compressed. Only 

 two ossified basibranchials (copulæ) are present; the first (coj) follows immediately 

 behind the glossohyal; its anterior end is without cartilage, the cartilaginous post- 

 erior end joins the cartilaginous front end of the second basibranchial (con); the 

 posterior end of the latter reaches the hypobranchials (hy) of the second gill- 

 arch. Sometimes an indication of a third basibranchial is found midway between 

 the second and third arches in the shape of a weak lenticular nodule of car- 

 tilage. 



As in Aulostoma and Fistularia the parts of the branchial arches belonging to 

 the roof of the pharynx are reduced. The first gill-arch has only two parts, the ce- 

 ratobranchial (ci) and the epibranchial (ej); the latter is rudimentary and widely 

 separated from the first. The lower end of the ceratobranchial is completely 



39* 



