294 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



oval in outline; they consist of an aggregation of ocelli. The- 

 Maxillipedes are broad, lamellate structures, and of comparatively 

 large size. Their inner margins meet in the median line, and are 

 nearly straight. A short, thick palpus, of three joints, is borne by 

 each Maxillipede on its upper and outer margin, in front of which it 

 projects. The under-lip is attached to the Maxillipede, and is pro- 

 duced externally to it. The second pair of Maxillae is flat, foliaceous, 

 and of the same breadth throughout. It bears a cap of chitine on 

 its upper and inner angle. The inner or first pair of Maxillse 

 possesses both endopodite and exopodite ; the latter is considerably 

 the longer and stouter, and bears five inwardly-curved chitinous 

 denticulations, and its outer border is beset with fine setae. The 

 endopodite is composed of two joints, both slender, the upper one 

 tipped with two feather-like setae. The Mandibles are strong and 

 of considerable thickness, being cii'cum scribed by a horny skeleton- 

 and bearing three bluntly pointed teeth at their apex, and patches 

 of fine setae on their inner and outer edges. The Labrum, above the 

 Mandible, is apparently a paired structure. It protects the oi-al 

 aperture. In structure it is foliaceous, and may be regarded as a 

 median growth of the sternum of this region. 



The Thoracic Appendages, seven in number, bear a strong simi, 

 larity one to another. They are composed of seven joints, and none 

 are chelate. A more exact description of them then followed. 



Of the six abdominal appendages five are concealed under the 

 abdomen— the uropods (appendages of the sixth somite) projecting 

 behind. The various modifications of these abdominal appendages in 

 the sexes then is dv/elt upon at some length. 



The uropods are alike in both sexes, and consist of a basal seg- 

 ment bearing two rami. 



The President, for Dr. Robert Bell, of Ottawa, read the 

 following paper on " The Mode of Occurrence of Apatite in 

 Canada," by Robert Bell, B.A.Sc, M.D., LL.D., Assistant 

 Director of the Geological Survey of Canada : 



The mode of occurrence of apatite in the crystalline rocks of 

 Ontario and Quebec, has been a puzzling question to geologists ever 

 since the mineral has been known to exist among them m quantities 

 of economic value. A number of contributions to a knowledge of 



