208 THE ENTOMOLOGIST. 



Section 4. — Abdomen more or less red ; apical segments not pale marked. 



A. Thorax and abdomen more or less red or chestnut, as well as greater 



part of legs ; antennce of female white-ringed. 1. nifus, 5 lines. 



B. Thorax black. 



a. Scutellum black ; ring of antennae wliite ; 1st and 3rd and base of 



4th abdominal segments red ; legs nigro-fuscous. 



13. soiiirufus, '^\ lines, female. 



b. Scutellum white ; apical margins of 1st and 3rd segments red ; 2ud 



red, with a brown dorsal spot ; front coxte and trochanters marked 

 with white ; femora and tibise red, apex of hinder black. 



9. tridmjulatus, 3^ lines, male. 



Section 5. — Abdomen red and black, with the apex marked with white. 

 Scutellum white or whitish (except in Nos. 10 & 11). 



Legs red ; coxse, trochanters and apex of hind femora and tibiae 

 black. 



A. Gastrocfeli obsolete ; metathoracic spiracles linear. 



Abdominal segments, 2nd and 3rd red, 1st and 2nd partly so ; 

 apex of 5th to 7th and ring of antennae white. 



12. errabundus, 4 — 4^ lines. 



B. Gastrocaeli distinct. 



a. Metathoracic spiracles oval. 



Segments, 1st to 4th or 5th, red ; petiole often black ; 6th and 7th 

 extreme apical margins and ring of antennae white. 



7. orhitalis, 3^ — 4^ lines. 



b. Metathoracic spiracles round. 

 * Scutellum white. 



Segments, 1st to 4th or 5th, red; 6th and 7th white at the apex ; 

 antennae of female white-ringed. 

 f Antennae of male white-ringed. . - 8. vgIuUUs, 3 lines [1). 

 If Antennae of male not white-ringed. - 14. j^f^ctor, 2i — 4 lines. 

 =:==;= Scutellum black; sometimes red iii diinidiatus ; antennae white- 

 ringed ; segments, 1st to 3rd, red (a var. of male in n'ujricoUis, 

 with 1st and part of 2nd black). 

 I 5th to 7th abdominal segments with wide white apical margins. 

 Thorax and hind coxae more or less red ; sometimes in the male 

 black. .... 10. dimidlatus, 3 — 4 lines [t, I). 



\\ 5th to 7th abdominal segments with narrow white apical margins. 



11. nlgricollis, 2f — 83 lines {a). 



This genus is rather rich in species, and as there is but little 

 sexual variation in them this is not mentioned in the table. It is 

 arranged by Holmgren according to the shape of the metathoracic 

 spiracles (in some species they are circular), the absence or 

 presence of metathoracic spines, the shapes of the scutellum and 

 grastrocseli ; we have preferred following Wesmael's colorational 

 grouping, as more in uniformity with Desvignes' divisions, 

 previously used in this family. None of our species of Platylahus, 

 except perhaps P. ijedatorlas, can be called common; bright 



