Morphological Studies. 751 



Description of Plates. 



Alphabetical references. 



dp dental papilla, e enamel, ee enamel epithelium, Ti horn, h g horn 

 groove, odontoblast, oc odontoblast cone, oe outer epithelium of ena- 

 mel organ, p c pulp cavity, s e stratified epithelium, s s tooth sacs. 



Plate XXXIV. 



Fig. 1. Longitxidinal section of apex of a lingual tooth of Sdellostoma, 

 to show the horny layer (h), the apex of the odontoblast cone (o c), 

 and the enamel cap. Zeiss, C. oc. 2 cam. lue. Mag. 120. 



Fig. 2. Diagram to illustrate the supposed mode of development of 

 a Myxinoid tooth. For comparison with the figure on p. 484 of 

 Wiedeesheim's Lehrbuch der vergleichenden Anatomie der Wirbel- 

 thiere, 2. Auflage, 1886. 



Fig. 3. Portion of mouth epithelium (transverse section) of a nearly 

 metamorphosed Petromi/ßon planeri showing three tooth sacs (ss) 

 and the first horn formation (A), odontoblasts are absent. 



Fig. 4. Odontoblasts from a Myxinoid tooth. Highly magnified. Zeiss 

 F. oc. 2. Mag. 460. 



Fig. 5. Apex of a tooth of Myxine to show the small cap of enamel 

 (e) under high magnification. Longitudinal section. Zeiss F. 

 oc. 2. Mag. 460. 



Fig. 6. Portion of enamel epithelium from the same Sdellostoma tooth- 

 section as fig. 8, e e enamel epithelium, o c odontoblast cone. 



Fig. 7. Semi - diagrammatic figure of a complete section of a tooth of 

 JBdellostoma to show its anatomy. About twenty times the nat- 

 ural size. 



Fig. 8. Small portion of a median tooth of Bdellostoma in longitudinal 



