NO. 6 PREPARATION OF COLEOPTERA VALENTINE 9 



the cement is mixed. Good adhesion with a minimum droplet of 

 cement depends, of course, upon the consistency of the latter, which 

 should not be so thick as to provide poor capillarity, nor so thin as to 

 spread beyond the original confines of the droplet. 

 Advantages : 



1. An assemblage of specimens illustrative of a circumscribed popu- 

 lation or of an ecological sample of a species provides far more 

 valuable data than isolated specimens and should be kept intact under 

 the same label. The slip method of mounting' makes this possible for 

 large specimens as well as small, and promotes comparison of 

 individuals. 



2. Too often the customary procedure of mounting small, flexed 

 insects on cardboard points results in specimens whose appendages 

 and ventral anatomy are seriously obscured by the adhesive. Another 

 handicap to study frequently arises from undue arching of the body 

 and depressing of the head. The transparent-slip technique allows 

 maximum visibility of all parts, which, in all but the most convex 

 forms (some weevils, mordellids, etc.), can easily be arranged so as 

 to appear nearly on one plane. Under these conditions, buccal and 

 appendicular anatomy and comparative dimensions of legs, etc., can 

 be observed with a maximum degree of ease. 



3. One of the commonest causes of damage in a collection is the 

 inadvertent contact between protruding labels and specimens deli- 

 cately mounted on points. The slip method obviates this hazard. 



4. Mutilation of specimens and interference with hand-lens exami- 

 nation by pins thrust through elytra are eliminated. 



5. Labels under acetate mounts are readable from above ; usually 

 they can be larger than the minimum-sized label customarily attached 

 to specimens mounted individually. 



6. A great saving of time is effected when specimens are mounted 

 in series by reducing the number of labels necessary and speeding 

 up transfer. 



7. Space is conserved through the close approximation of specimens 

 on the mounting slip. 



8. Far fewer pins are used. 



9. The problem of which method of mounting — pin or point — 

 should be applied to a rather small specimen is eliminated ; this makes 

 for uniformity in the collection. 



10. Any specimen can instantly be removed from the acetate mount 

 merely by touching it with a brush containing ethyl acetate. 



b. Cover-glass mounting. — This is a refinement of the above tech- 

 nique, micro cover glass (No. i or No. 2) being used in place of 



