The insects that form the genus GasteropJtilus are very re- 

 markable for their economy : the eggs, or young caterpillars, 

 are swallowed by the horse, and remain in the stomach of that 

 valuable animal, exposed to a temperature of 102 degrees of 

 Fahrenheit, until full grown, when they pass through, and 

 fallino- upon the ground become pupae, and afterwards flies, 

 the females exhibiting an instinct in selecting the peculiar 

 places upon the animal to deposit her eggs, which is truly 

 astonishing. Their habits are not only widely different from 

 those of the group we have given at folio 106, but the perfect 

 insects may be without difficulty separated by the nervures of 

 their wings. I suspect that portion of the antennae which I 

 have called the 2nd joint in the characters of (Estrus is only 

 the narrowed base of the large joint, and the basal joint of the 

 seta in our present genus may be nothing more than the scape. 

 Five species have been recorded as British. 



1. G. Equi Clark, pi. 1. f. 1-16. — Bovis Linn. 



It is found in August and September flying about horses 

 and in heathy districts, which I was not aware of imtil this 

 autumn, when in the Isle of Wight I saw 8 or 10 flying round 

 a small space where no cattle were, they looked like bees, and 

 made a considerable humming with their wings. 



2. G. salutiferus et salutaris Clark, pl.l. f. 33-36. 



For specimens of this rare insect I am indebted to Mr. Bra- 

 cey Clark, who found the larvae in the stomach of a horse at 

 the entrance of the pylorus, and taking them from their situa- 

 tion, they were forced down the throat of his own horse, and 

 received again on their exit after some months ; and from the 

 pupse the identical male here figured, as well as females, were 

 produced. 



3. G. haemorrhoidalis Lhm. Clark, pi. \.f. 17-23. 



Seen flying about the mouths of cattle upon commons in 

 the month of August. 



4. G. nasalis JJnn. — veterinus 'Fab.^ Clark, pl.l. f. 24-27- 



Panz. 107-21. 



5. G. Clarkii LeacNs Arrangement, pi. 2. 



Was taken by Dr. Leach at Kingsbridge, Devon, and 

 named after the gentleman whose Essay upon the subject we 

 strongly recommend to the perusal of the student. 



The plant is Arahis ihaliana (Common Wall Cress). 



