LAKVAL FORMS OF COLEOPTERA 



Tergal shields tuberculate ; with fan shaped hairs. 

 Micropeplklae (f) 



F. HYDROPHILOIDEA 

 This series is not identical with the series named Hydrophiloidea 

 in the classification of the imagines bnt it is considered expedient 

 to retain the serial name Hydrophiloidea for the present associa- 

 tion of families which according to their larvae constitute a homo- 

 geneous nnit and to which the genus Hydrophilus belongs. The 

 Histeridae are included in this series on account of an unquestion- 

 able conformity in the development of the fundamental systematic 

 characters in the larvae of the Histeridae and Helophoridae. The 

 Limnebiinae, Hydraeninae, and Hydroscaphidae of the authors 

 belong in the series Staphylinoidea according to the form of their 

 maxillary palpigers and spiracles. 



Key to Families and Subfamilies 



1. Nine complete abdominal segments; tenth small. (First to 



eighth abdominal spiracles lateral and well developed) 2 



Eight complete abdominal segments. (Ninth and tenth re- 

 duced ; first to seventh abdominal spiracles lateral and small 

 or apparently absent, eighth abdominal spiracle terminal, 

 sometimes poorly developed ; usually with a terminal breath- 

 ing pocket; occasionally with gills) 3 



2. Cardo fused with stipes; one ocellus {Epierus) or none; coxae 



small and widely separated. (Tarsus either short and falci- 

 form, or long, flexible and terminally filiform ; urogomphi 

 of moderate length and usually tv.'O-jointed, or short and 

 two-jointed with proximal joints fused at base in Plegadenis 

 and Epierus, or reduced to a pair of warts. Some ter- 

 mitophilous larvae from British Guiana with rather stiff, 

 digitiform processes on the sides of the body, one pair to each 



segment) Histeridae*^ (pis. 20 A-R and 21 I) 



Cardo distinct; six ocelli; coxae large, approximate. (Tarsus 

 falciform ; urogomphi diverging, long, three-jointed, taper- 

 ing into a thread-shaped end ; mandibular penicillus very 

 ^'^' The Pselaphidae and Scydmaenidae are very closely related, 

 differing mainly from each other in the form of the antennae and 

 the size of the abdominal spiracles in proportion to the size of the 

 thoracic spiracles. According to the larvae, the Scydmaenidae 

 may have some connection with the Scaphidiidae, but like the Psel- 

 aphidae they approach more closely to staphvlinid genera like 

 Bledius. 



■'^ The subfamilj' Hololeptinae with the genus Hololepta as type 

 can not be retained in the classification of the larvae. 



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