RHINOCEROS. 597 



with an irregular and, in some parts, slightly curved course, but 

 he could not consider them as being undulated : they were g-s^^th 

 of an inch in diameter at their beginning, soon bifurcated, and 

 gave off very numerous branches ; the interspaces between the 

 origins of the tubes, equalled the breadth of two tubes. The 

 peripheral part of the dentine, close to the investing layer of cement 

 contained a dense stratum of opake cells, in which many of the 

 branches of the calcigerous tubes terminated ; the extremities of the 

 tubes meander through the interspaces of the cells, some terminating 

 in the cells, other anastomosing with adjoining tubes in beautiful 

 curves. 



I have examined the microscopic structure of the molar of the 

 Indian Rhinoceros, in vertical and horizontal sections of the crown. 

 The pulp-cavity is continued in the form of fissures, into the middle 

 of the eminences bounding the valleys of the uneven-grinding 

 surface, and a few short vascular canals are continued into the 

 dentine from the summits of the pulp-fissures, especially at their 

 terminal angles. In horizontal sections dividing the vascular canals, 

 their arese appear like large opake cells, with a clear border, and 

 the adjoining dentinal tubes diverge, as it were, to give place for 

 them : the ends of a few tubes, which were given off from those canals 

 being seen in the clear border. Retzius makes mention of larger 

 groups of opake cells in the middle of the dentine of the root of 

 the molar, which seemed to have forced aside the main-tubes, which 

 bent round these groups of cells, and sent off some branches which 

 there terminated. 



The major part of the coronal dentine of the Rhinoceros's 

 molar, is fine-tubed and unvascular : I found the dentinal tubes, 

 at their origin from the pulp-fissure, to have a diameter of ~[\\ 

 of an inch, with interspaces averaging ^th of an inch. They 

 ascend (in the lower molar), inclining at first very slightly from the 

 pulp-fissure, and gradually bending more outwards w^ith the con- 

 vexity of the curve upwards, until near their termination, when 

 they gently curve in the opposite direction. Throughout their 

 course they are undulated, the secondary waves being pretty regular 

 and stronger than in the Human dentinal tubes. Transparent tracts, 



