DIP 



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DIP 



inclination of strata. The point of 

 the compass towards which strata 

 incline is called their dip, and the 

 angle of such inclination with the 

 horizon is termed the dip, or angle, 

 of inclination. It sometimes hap- 

 pens that a stratum, without vary- 

 ing its direction, may be so bent 

 as to dip two ways in the same 

 mountain, like the sloping sides of 

 the roof of a house, or the letter V 

 reversed A. 



DrpE'TALous. (from &V and TreVaXoi/, 

 Gr.) Having two flower-leaves or 

 petals. 



DIP'LACANTHTJS. (from dta-Xco s, double, 

 and aicavOa, a spine, Gr.) A genus 

 of ich thy olites or fossil fishes, found 

 in the old red sandstone by Hugh 

 Miller and thus described by him, 

 "though the smallest ichthyolite 

 of the formation yet known, it is 

 by no means the least curious. 

 The length from head to tail in 

 some of my specimens does not 

 exceed three inches; the largest 

 fall a little short of five. The 

 scales, which are of such extreme 

 minuteness that their peculiarities 

 can be detected by only a powerful 

 glass, resemble those of the Cheira- 

 canthus. There are two dorsals, 

 the one rising immediately from 

 the shoulder, the other directly 

 opposite the anal fin. The ventrals 

 are placed near the middle of the 

 body. But the best marked char- 

 acteristic is furnished by the spines 

 of its fins, which are of singular 

 beauty. Each spine resembles a 

 bundle of rods, or rather the sculp- 

 tured semblance of a bundle of 

 rods, which finely diminish towards 

 a point, sharp and tapering as that 

 of a rush. The rest of the fin 

 presents the appearance of a mere 

 scaly membrane, and no part of 

 the internal skeleton appears. The 

 spines run deep into the body, as a 

 snip's masts run deep into her 

 hulk." Agassiz has enumerated 

 four species j D. crassispinus, D. 



longispinus, D. striatulus, and D. 

 striatus. 



DIPLO-NEFRA. See Helminthoida. 



DIPLO'PTEEOTJS. The name given by 

 M. Agassiz, to a genus of ichthyo- 

 lites, belonging to the family of 

 Sauroid fishes, and found in the 

 old red sandstone. "Like the 

 genus dipterus, it has two dorsal 

 opposite two anal fins, but the 

 caudal fin is of a very peculiar 

 form ; the throat is very large, and 

 the jaws are armed with large 

 conical teeth." Murchison. Silu- 

 rian System. 



DI'PTERA. (from ls and Tnepov, Gr.) 

 The sixth order of insects, or 

 insects having two wings. The 

 musca, or common fly ; the culex, 

 or gnat ; and the oestrus, or gad- 

 fly, are familiar examples. In 

 Cuvier's arrangement diptera forms 

 the twelfth class of insecta, and 

 their distinguishing characters are 

 said to be possessing six feet, and 

 two membranous extended wings, 

 accompanied generally by two 

 moveable bodies, called halteres, 

 which are placed behind the wings ; 

 the organs of manducation are a 

 sucker composed of squamous, sec- 

 taceous pieces, varying in number 

 from two to six, enclosed in an 

 inarticulated sheath, most frequent- 

 ly in the form of a proboscis. In 

 these divisions almost every ento- 

 mologist is disposed to make 

 alterations, and the systems pro- 

 posed are far too numerous to be 

 recounted. 



DI'PTEROUS. Two-winged insects ; 

 belonging to the order Diptera. 



DIPTERUS. (from Js, twice, and 

 trrepov, a wing, Gr. Double wing.) 

 A genus of ichthyolites, belonging 

 to the old red sandstone, established 

 by Cuvier. This genus, says Sir 

 B. Murchison, was at first separated 

 by Valenciennes and Pentland into 

 four species, but after an attentive 

 examination of a great variety of 

 specimens, M. Agassiz has con- 



