3J2 NATURAL ARRANGEMENT OF INSECTS, 



plication in their neuration than the preceding. They 

 form a large host, and are divided into three families, 

 viz. the Notacantha, the Tanystoma, and the Brachy- 

 stoma. The first family,, or JVotacantha, are distin- 

 guished by having the third joint of their antennae 

 annulated, thus somewhat resembling the Hexachcetce. 

 They are all more or less characterised by the spines of 

 their scutellum. whence their name ; and they form 

 three tribes the Sicarii, the Xylophaga, and the Stra- 

 tiomycB. The larvae of the second of these have been 

 observed to live in putrescent wood. The Brazilian 

 genus, Hermetia, in the same tribe, is peculiar for the 

 pellucid spots at the base of the abdomen. Xylophaga 

 is an extremely rare British genus. The third tribe, 

 the Stratiomyce. are all more or less attached to the 

 water or its vicinity. Thus, Stratiomya is found only 

 in such situations, and its larva occurs in stagnant pools; 

 this is elongate,, and depressed, and attenuated at the 

 posterior extremity ; and these insects are constantly 

 found upon aquatic flowers; whereas the brilliantly me- 

 tallic Sargus settles only upon foliage. The bodies of 

 all these insects are considerably depressed, and their 

 wings have a central, rather large, cell. Ephippium is 

 of very rare occurrence as a British insect ; and is of an 

 intense black, with a bright red thorax : none of the 

 family are of large dimensions. 



(333.) The second family, or Tanystoma, contains 

 the giants among the Diptera, and includes insects of 

 great variety of habits and of forms. Their combining 

 character is, however, to have the third joint of their 

 antennae simple, with a terminal seta ; a coriaceous ros- 

 trum, which is usually slender and lengthy. The Asi- 

 HdcB are probably the most typical; and are very rapa- 

 cious insects, feeding upon every thing else that they 

 can conquer. Megapoda is remarkable for its lengthy 

 slender legs and large size, and is peculiar to the Brazils; 

 whence also Mallophora, with its hairy body, comes, and 

 which, thus much, resemble, the Bombi. Dasypogori, 

 Dioctria, and Asilus are native genera, and the latter 



