6*-^ 



ON THE GENERAL MORPHOLOGY OF THE MYXINOID FISHES. 



681 



EXPLANATION OF THE PLATE. 



Reference Letters. 



a. d. p. Anterior arch of the dental plate. 



a, d. p. Posterior external ) r , 



r > processes of above. 



a. d. p . Posterior internal ) 



a. t. b. Anterior transverse bar of the nasal cap- 



sule. 

 a. t. v. b. Anterior transverse velar bar. 

 an. c. Auditory capsule. 

 au. f. Auditory foramen. 



b. jo. 1-3 Anterior, middle, and posterior segments 



of the basal plate. 



br. a. 1 First "branchial" arch. 



br. a.- Second "branchial" arch, consisting of 

 separated upper and lower divi- 

 sions. 



c. c. Cornual cartilage. 



cr. Membranous cranium. 



d. t. Median dorsal tooth. 



e. b. p.' External bar of the anterior segment of 

 the basal plate. 

 e. I. b. External lateral velar bar. 

 /, 1-4 The four fenestra of the skull. 

 li. p Hypophysial plate. 



h. p.' Rod connecting above with the posterior 

 transverse bar of the nasal capsule. 



hy. "Hyoid" arch. 



i. b. p.' Internal bar of the anterior segment of the 



basal plate. 



i. I. b. Internal lateral velar bar. 



i. I. c. Inferior lateral cartilage. 



I. I. c. Lateral labial cartilage. 



/. p. Lateral plate of the nasal capsule. 



n. c. Nasal capsule. 



nl. Notochord. 



pc. "Parachordal" cartilage. 



p. d. p. Posterior arch of the dental plate. 



pi. " Palatine " bar. 



p. q. " Pterygo-quadrate." 



p. I. b. Posterior transverse bar of the nasal cap- 

 sule. 



p. t. o. b. Posterior transverse velar bar. 



s. I. c. Superior lateral cartilage. 



■sn. b. Subnasal bar. 



sp. c. Membranous neural tube. 



tr. Trabecula. 



Fig 1. Reconstruction from serial sections of the left side of the skull of a 25 cm. Hag. x 14f. Ten- 

 tacular cartilages and the rings of the nasal tube numbered from before backwards. The colours and shading 

 indicate the different kinds of cartilage, and also the staining reactions of the same with Mann's methyl- 

 blue-eosin : hard cartilage, red ; soft cartilage, blue ; hard pseudo-cartilage, blue (dotted) ; soft pseudo- 

 cartilage, uncoloured and obliquely striated. 



Fig. 2. Reconstruction from serial sections of the dorsal surface of the skull of the same Hag. x 14§. 

 Tentacular cartilages numbered from before backwards. The "branchial arches" have been displayed for 

 the sake of clearness, and this involves an artificial lengthening of the first branchial arch, and also a lateral 

 displacement of the external lateral velar bar. This, however, does not affect the correct delineation of the 

 parts in the longitudinal plane, and hence the two figures may be strictly compared. Nasal tube and capsule 

 removed and the dental skeleton not shown. Tentacular apparatus seen in perspective, and, apart from the 

 sigmoid twist, cannot be so accurately shown as in a lateral view. Anterior pseudo-cartilage cap of the 

 basal plate omitted, nor can the bending of the hypophysial plate be shown. Colours, etc., as in fig. 1. 



It should be pointed out here that in Part I., owing to a misunderstanding with the lithographer, fig. 16 

 was laid down on the stone the wrong way. The figure is quite accurate, but the sides must be reversed. 

 If the plate be held up with the figure towards the light the correct ventral view is obtained, the structures 

 on the observer's right belonging to the animal's left, and vice versa. 



TRANS. ROY. SO(J. EDIN., VOL. XLVI. PART III. (NO. 24). 



100 



