THE SUCTORIA. 363 



body greatly lengthened, the head distinct, and a great 

 number of feet. III. The CRUSTACEA, or crabs, which 

 are enveloped by a hard or crustaceous covering ; live 

 in the water, and breathe by branchiae ; the head being 

 apparently confounded with the thorax. IV. The SUC- 

 TORIA, or fleas : the body is compressed, and covered 

 transversely with hard and. polished plates, and with four 

 minute scales, which indicate the position of the wings 

 of flying insects. V. The DIPTERA, or two-winged 

 insects, which, like the last order, imbibe their nourish- 

 ment by suction. 



(322.) The isolated position which belongs to the 

 fourth of these orders, is, we apprehend, entirely caused 

 by the fact of its containing not more individual species 

 than would form a sub-genus, while, in itself, it ranks 

 as an order : this rank has been assigned to it ever since 

 the days of De Geer, who was the first writer that thus 

 detached it; arid whose name of Suctoria we shall retain, 

 in common justice to so great a man. We shall not 

 enter into the conflicting opinions of the moderns re- 

 lative to the situation of these singular insects ; for a 

 chapter might be so filled, and the reader, in the end, 

 left pretty nearly in the same state of uncertainty as at 

 first. We would simply call the attention, even of the 

 most unscientific, to those little crustaceous insects so 

 common among sea- weed on sandy shores, and then ask 

 him what insects can possibly be more like, in habits 

 and appearance, than these are to fleas ? their very name 

 of sand fleas at once shows that this resemblance is so 

 strong that every body perceives it ; and however the 

 two may differ, when we come to anatomical details and 

 technical refinements, these will never alter the similitude, 

 or persuade an unscientific person that they do not come 

 wonderfully near to each other. We consider, therefore, 

 that the order Suctoria is more clearly related, by affi- 

 nity, to the Crustacea than to any other ; but this being 

 admitted, we confess our entire ignorance of what re- 

 semblance it has to the Diptera, beyond the fact of both 

 being perfectly suctorial orders. The only great hiatus., 



