10 



11 



12 



13 



14 



15 



16. 



17. 



18. 



19 



20. 



21 



22. 



Urogomphi solidly united at base, or absent 15 



Maxillary palpiger free and segmentlike, usually carry- 

 ing a finger-shaped galea; spiracles biforous; HYDRO- 



PHILOIDEA 11 



Maxillary palpiger closely united with stipes, without 

 finger-shaped galea; spiracles annular or absent; ocelli 



in groups of 5. STAPHYLINOIDEA 12 



With only 1 or no ocelli on each side of head; 9 com- 

 plete abdominal segments, 10th small; mostly terrestial 



but occasionally littoral HISTERIDAE 



Ocelli usually in groups of 6; usually with 8 complete 

 abdominal segments (9 in Helophorus) (figs. 13:37, 



13:38) HYDROPHILIDAE 



Mandible lacking asperate or tubercular molar portion, 

 usually without molar parts; some littoral species. 



STAP1IYLINIDAE 



Mandible with molar part usually large, asperate or 



tubercular 13 



Tenth abdominal segment provided with a pair of 



recurved hooks (fig. 13:28) IIYDRAENIDAE 



Tenth segment lacking terminal hooks 14 



Spiracles absent; balloonlike appendices on pro- 

 thorax, 1st and 8th abdominal segments; antenna very 



short and 2-segmented (fig. 13:42o-ci) 



HYDROSCAPHIDAE 



Spiracles present; no balloonlike appendices; antennae 

 3-segmented; mandibles multiserrated .... PTILIIDAE 

 Ninth abdominal segment with a ventral movable 



operculum closing a caudal chamber 16 



Ninth abdominal segment without operculum 19 



Caudal chamber with 2 prehensile claws and 3 tufts 



of retractile gills 17 



Caudal chamber without prehensile claws, with or 



without 3 tufts of retractile gills 18 



Form robust with head retracted into 1st thoracic 

 segment out nearly as wide as thorax or abdomen; 

 thorax with pleura sclerotized but sternites absent 

 or membranous, abdomen with pleura set off by sutures 



on segments 1-4 LIMNICHIDAE 



Form usually more slender, head more or less retracted 

 into 1st thoracic segment but thorax widening pos- 

 teriorly, sternites present or at least venter sclero- 

 tized from side to side; abdomen with 6 to 8 pleurae 

 set off by sutures (rarely with sutures obliterated or 



indistinct) (fig. 13:50) ELMEDAE ' 



Body form cylindrical in cross section, without tufts 

 or retractile gills; abdominal sterna and pleura greatly 

 reduced on segments 1-5 and aosent on segments 

 6-9, terga forming a complete sclerotized ring, ab- 

 dominal spiracles on segments 1-7 lateral, on 8 dorsal 



DRYOPIDAE 



3ody form greatly flattened with margins extended 

 so as to resemble a suction cup; cloacal chamber 

 containing 3 tufts of fingerlike gills (fig. 13:59) 



(in part) PSEPIIENIDAE 



Four or more of the first 7 abdominal segments bear- 

 ing 2 ventral tufts of filamentous gills 20 



Abdominal segments without such gills 21 



Body greatly flattened with margins extended so as 

 to resemble a suction cup; with ventral gills on 4 or 

 more of the first 6 abdominal segments (fig. 13:59) 



(in part) PSEPIIENIDAE 



3ody form elongate cylindrical; with gills on under 



side of abdominal segments 1-7 



(in part) PTILODACTYLIDAE 



With gills restricted to anal region, more or less in 



a caudal chamber 22 



Without conspicuous gills 23 



Body form elongate cylindrical; 9th segment with 5 

 to 21 mamillae-form "gills" and 2 prehensile curved 

 appendages covered with short, stout spines in a 

 shallow caudal chamber; lateral spiracles on first 

 8 aodominal segments . . .(in part) PTILODACTYLIDAE 

 Body form more eliptical and flattened; 8th segment 

 with gills in the terminal caudal chamber and a pair 

 of enlarged spiracles on the apex above; other spir- 

 acles vestigial or absent, 9th abdominal segment 



299 

 Leech and Chandler: Coleoptera 



vestigial; 3rd antennal segment multiarticulati- . I 

 and tapering (fig. 13:46) JIKI.OIMI) AK 



23. Ninth abdominal segment without UTOgOmphi, if .solidly 

 ohitinlzed it is .similar to the anterior segment and 

 without hornlike projections 24 



— Ninth abdominal segment conspicuous with urogomphi 

 fused at base and immovable or more heavily chitinizod 

 with various hornlike projections 25 



24. Mouth parts directed anteriorly, maxillae large and 

 conspicuous; legs well developed; abdominal segments 

 1-9 similar in form, each with a lateral spiracle and 

 with a solid tergito covering dorsal half of segment; 

 littoral IIETEROCERIDAE 



— Mouth parts ventral, maxillae normal, distinct gular 

 region or gular suture absent; mandibles either simple 

 or possessing a pseudomola; legs often poorly de- 

 veloped; abdominal segments mostly membranous, 

 or with small, well-separated sclerites, 9th segment 

 much smaller than others; habits: surface feeding 

 or submerged on stocks and roots (fig. 13:60a, b) ... 



CIIRYSOMELIDAE 



25. Abdominal spiracles located in disclike scleromes; 

 urogomphi branched with outer prongs curved out and 

 inner prongs strongly curved in; intertidal zone, sea- 

 shore .(fig. 13:45) EURYSTETHIDAE 



— Abdomina.l spiracles not located in disclike scleromes, 

 urogomphi not branched thus; not truly aquatic but 

 some species found in the littoral zone 26 



26. Maxillary articulating area either large or indistinct; 

 when it is indistinct, mandible has a mola; without 

 lacinia mandi'oulae 27 



— Maxillary articulating area absent, or very small, or 

 concealed by mentum, not large and cushioned; man- 

 dible with lacinia mandibulae but lacking molar part 



MELYRIDAE 



27. Mandible with a fleshy, hairy lobe behind base of 

 mola; hypopharyngeal sclerome small, cup-shaped, 

 on top of slightly chitinized dome; 1 ocellus on each 

 side of head ANTIIICIDAE 



— Mandible without such a lobe, hypopharnynx with 

 sclerome at base TENEBRIONIDAE 



28. Mouth parts terminal, body mostly membranous with 

 pro-, meso-, and metatergum and propleurae and ster- 

 num chitinized, 8th abdominal segment more or less 



C-- truncate, terminated by a flat plate below which is 

 9th segment bearing 2 large spiracles; Cercyon in 

 HYDROPHILIDAE 



— Mouth parts ventral, body membranous except for pro- 

 tergum; no dorsal plate on 8th abdominal segment 



CURCULIONIDAE 



Family CARABIDAE 



Ground Beetles 



This is one of the four largest families of beetles; 

 like the Staphylinidae, it has some 20,000 described 

 species in the world. 



Two small, flattened kinds of the genus Thalasso- 

 trechus have been described from the intertidal zone 

 of the California coast, but they appear to be northern 

 and southern forms of one species, intergrading north 

 of Santa Barbara. They have strongly prognathous 

 mandibles, stout, well-separated legs, but no wings. 

 They and their larvae can readily wedge themselves 

 into cracks in rocks which are submerged at high tide, 

 and presumably can make use of air trapped there. 

 As they are predators they may find their food in 

 such crevices, though they are capable of foraging 

 elsewhere while the tide is out. 



There are related genera of harpaline Carabidae 



