(J8 DR- W. E. COLLINGE ON THE 



hours. Finally, it was again placed in a 15 °/ solution of HC!1 for ten to 

 sixty minutes. After further careful washing the specimen was dehydrated 

 and then stained with Meyer's alcoholic carmine. 



Most of the material was examined in xylol, some was mounted in Canada 

 balsam (xylol) and some in Farrant's solution, but none of the specimens 

 were improved by the use of either of these media — the former proved the 

 better of the two. 



I should strongly recommend anyone trying this method to first experiment 

 with some material of no value, as it is only by experience that one comes to 

 appreciate just the right time to remove the specimens from one solution 

 to another. If removed too soon little change has taken place ; on the other 

 hand, a very short excess period is sufficient to ruin the object. 



If the above-mentioned small flat glass dishes are used the specimens can 

 be examined from time to time under a low-power of the microscope and the 

 progress and changes noted. 



The value of this method of treating small, jointed chitinous objects lies 

 in the fact that, if carefully handled, little or no displacement of the different 

 parts takes place ; further, the objects are rendered perfectly transparent, all 

 cellular tissue and pigment being removed, and a uniform stain is taken up 

 by the margins of all joints, segments, spines, etc. Setse which appeared to 

 arise as stiff spines from the surface of a body can, by this method of 

 preparation, be seen to pass beneath the surface at their proximal ends and 

 to be lodged in tiny pits or articular cups, whilst others that appeared to be 

 perfectly smooth are found to carry smaller spines, teeth, etc. 



It is with considerable pleasure that I here acknowledge my indebtedness 

 to Professor Irvine for the basis of this method, and for the, at all times, 

 kindly criticism and advice he has given. 



III. The Oral Appendages of the Family Idoteid^e. 



The two principal appendages that have been employed in the classification 

 of the members of the suborder Valvifera are the first maxillas and the 

 maxillipedes, and I propose to offer some few remarks upon these as 

 presented in the family Idoteidse. 



The First Maxillce. — Each maxilla consists of a pair of elongated chitinous 

 bodies — the inner and outer lobes — connected by a small basal segment. The 

 outer lobe is slightly convex on the ventral side and almost flat dorsally, 

 usually the anterior half, or even two-thirds, is wider than the posterior 

 portion. Setulos, small plain spines, set in cup-shaped articular cavities may 

 or may not be present on the anterior part of the ventral surface. Distally 

 there are a variable number of curved spines. In many species these are 

 divided into two distinct sets, viz., an outer series of stout, curved, bluntly 



