79 



showing the relations of the latter to the other species to 

 which I have had access. The nomenclature of the bones 

 of the skull in this genus I found to be a subject of no 

 little difficulty, and I have been glad to avail myself of 

 that proposed by Professor Owen, in his recent lectures on 

 the Vertebraia. Previous to their publication I had sup- 

 posed that the border of the upper jaw of the Murance 

 was formed of the premaxillaries and maxillie arranged 

 nearly as in the salmon, but that the premaxillaries were 

 intimately anchylosed with the nasal and ethmoid bones, 

 forming the jaw and roof of the mouth back to the interior 

 pillar of the orbit, where the disk is embraced by the fore 

 part of the vomer. The maxillary also 1 considered as 

 united to the palate bones, these forming the interior 

 plates, which are more or less developed in different species, 

 and only occasionally dentigerous, and then generally sup- 

 porting tall, subulate teeth, like those on the mesial line of 

 the premaxillary disk. Finding on the strong mandibular 

 pedicle the small socket for the joint of the operculum, 

 and the symplectic knob for the pivot of the lower jaw, 1 

 had supposed this bone to be composed of the union of 

 the several parts constituting the Systema ptenjyoideo 

 temporale of Cuvier. 



The vertebra; next the head of the Muiieiue have a short, 

 neural spine, a horizontal parapophysial process on each 

 side, and a thin crest from the under surface of the cen- 

 trum, op]>osed to the neural spine, and which I might have 

 taken for a hismal spine but for the authority of Mr. 

 Owen, who denies that process to the fish. About the tenth 

 vertebra (in M. Helena, and not far from it in other spe- 

 cies) the mesial inferior crest divides and diverges on the 

 three succeeding vertebra; until it joins the transverse, 

 parapophysial process, to the extremity of which it adds 

 height by giving it a second angular corner. As the ver- 

 tebrae approach the anus the angular corners of the extre- 

 mities of the parapophysial processes separate more and 

 more from each other, the upper one remaining nearly 

 horizontal and the other turning more and more directly 

 downwards, until, with its fellow of the o]5posite side, it 

 forms a deep canal. Finally, at the end of the abdominal 

 cavity, and a considerable way past the anus, the canal is 

 closed beneath by the union of its sides, and a spine is 

 added to the arch of the ha;mal passage, very similar to 

 the neural one of the same vertebra, so that the vertebrae 

 of the posterior two-thirds of the tail possess a strong, 

 compressed neural spine, a horizontal parapophysis and 

 a haemal canal and spine, seemingly formed of the inferior 

 members of the parapophysis. Also there is a ridge at 

 the base of the neural spines, and another at the base of 

 the haemal ones, for the attachment of the membranes in 

 which the inferior and superior series of ribs lie. The up- 

 per row of ribs runs from the fifth or sixth vertebra to the 

 point of the tail, and the under one from the anus also to 

 the tip of the tail. Each rib is forked at the end next the 

 centrum, the shorter process having a small round head, 

 and the body of the rib being thickest in the middle, or 

 spindle-shaped. The stoutest ribs are situated a short 

 way behind the anus. 



The teeth are of two kinds, viz., slender or compressed, 

 and very acute, breaking in the using and dropping out; 



or conical and rounded on the summits, wearing flatter. 

 Some of the acute teeth are simply subulate ; others are 

 compressed-subulate, with an acute, diaphanous edge 

 before and behind, or they may be termed stiletto-shaped ; 

 such are the front teeth generally. In most species the 

 outer teeth on both jaws, posterior to the front of the or- 

 bit, are considerably reflex, and have a narrowly-lanceo- 

 late shape, also with acute edges. In a very few species 

 the teeth are serrated on the edge. The teeth stand on 

 the edge and disk of the nasal bone, the palatines, man- 

 dibles and vomer, sometimes in a single series on all these 

 bones, sometimes double on all, or in double and single 

 series variously combined on the several bones. 



In the following table the species are arranged in ac- 

 cordance with their dentition. 



A. Teeth acute, subulate, stiletto-shajjed. Gape large. 



a. Uiiiserial palatine teeth. 



1. Uniserial teeth on all the dentiferous bones. 



M. helena ; mibila ; sat/enedota ; reticulata ; ocel- 

 lata ; punctata ; similis. 



2. Teeth biserial in the front of the mandible, uniserial 



on the sides of the mandible and on the other 



bones. 

 M. pratbernon ; tenebrosa. 

 •3. Biserial teeth in the front of the mandible and hind 



part of the vomer; uniserial teeth on the other 



bones. 

 M. lita. 

 4. Biserial teeth on the nasal bone, on the front of the 



lower jaw and on the vomer. 

 M. siderea. 



b. Biserial palatine teeth. 



1. Uniserial nasal, mandibular and vomerine teeth. 

 M. isingleena ; bullata ; stellifer ; cancellata ; tes- 



sellata ; colubrina ; moringua. 

 Obs. — When the inner palatine teeth are only one or 

 two in number they are easily broken away, and the den- 

 tition then is similar to that of group A. I. 



2. Front mandibular teeth biserial ; vomerine and na- 



sal teeth uniserial. 

 M. griseo-badia ; pavonina. 



3. Nasal teeth pluriserial ; vomerine and mandibular 



teeth uniserial. 

 M. guttata. 



4. Teeth biserial on the front of the mandible and on 



the vomer; uniserial on the nasal bone and sides 

 of the mandible. 

 M. thgrsoidea ; sathete. 



5. Biserial on all the bones except the sides of the 



mandible. 

 M. gracilis ; vermiculata ; meleagris ; viridis. 



B. Gape moderate. Teeth conical, subacute or round- 

 ed. MOLARII. 



a. Palatine teeth uniserial, subacute. 

 M.ophis; variegata. 



b. Palatine teeth biserial, obtuse. 

 M. polgzona ; calennta. 



