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ring in the canal of the lower jaw, and fending filaments to 

 the denticuli on the edge of the mouth, and ending on the 

 point of the bill ; / the nafal branch of the ophthalmic di- 

 ftributed to the feptum. 



External Parts, or Inltgumcnts, 



T\^t feathers with which the bodies of birds are clothed, 

 render them lefs capable of receiving the more fimple im- 

 preffions of touch, than moft other animals. They alfo 

 ferve to defend them againft the exceffes of temperature. 

 The ftrudture and mode of growth of thefe fubftances are 

 confidered in another part of the dictionary. Sec Fea- 

 thers. 



The cuticle of birds is remarkably thin, but refembles in 

 flruiflure the epidermis of mammaha. It is Ihed generally 

 alongr with the feathers. 



The rete nmcofum is not obfervable, except in thofe parts 

 whieli are uncovered by feathers, and poffefs peculiar colours, 

 as the ceres and carundcs of the head, the feet, and bills ; 

 where it is of couife found to vai-y in colour as thofe 

 parts do. 



The cutis is in moft birds extremely thin and delicate in 

 its texture, appearing often hice a fine fitigle lamina, inftead 

 of an intermixture of fibres as in mammalia. It is, how- 

 ever, of iome ftrength in the ivater llrds and the asciphrcs ; it 

 is thinned in the pajjeres. The external part of the cutis is 

 never pcpiHate/i, bat when it covers the under furfaces of the 

 toes wbich are defigned to receive the imprefiio:is of external 

 bodies. 



The v.ufcles ofthcjk'in, in confeq'ience of the fize of the 

 external coveriiigs, are in general very evident, and par- 

 ticularly in thofe birds which move the feathers of the creft, 

 neck, or tail, as the hoopoes, cochaloos, herons, iyc. 



The following cntaneous mufclcs arc common to all birds. 

 Two flefhy (lips, which arife from behind each fide of the head 

 behind the mcat'js auditorius, and go backwards to be Ijft 

 in the integuments. A iliin expanfion pf mtifcle along the 

 anterior and lateral parts of the neck ; it takes a longitudinal 

 courfe, but is connected with fome tranfverfc fibres between 

 the jaws ; this mufcle correfponds with the platyfma myoi- 

 des. There is a mufcle, arifing in a ferrated manner from 

 two or three of the lower ribs, and extending upwards to 

 the axilla and outfide of the (houlder. We have perceived, 

 in the goofe, a ver)- thin flip of mufcle proceeding from the 

 pofterior part of the branch of the pubis to the ikin on the 

 infide of the knee ; and Cuvier confiders the red granular 

 appearance under the ikin on the back of the pelvis as muf- 

 cular fubftance. 



The functions of the fKin of birds, as an organ of abforp- 

 tion and excretion, appear to be verj' imperfect. The cloth- 

 ing of feathers alone difqualifies it in a great degree for the 

 performance of thefe procefies. The thinnefs and llmple or- 

 ganization of the fltin itfelf renders it probable that its fe- 

 cretory powers are but inconfiderable. It does not alfo pof- 

 fefs thofe various glands which are fo abundantly bellowed 

 upon the (liin of other animals for its prefervation and defence 

 againll the operation of external fubftances. Birds are, 

 however, provided with two peculiar glands for the pur- 

 pofe of furnidiing an oily fluid, to keep the feathers in order 

 and defend them againft the effects of nioiflure. 



The oil glands are two oblong or oval-lhaped bodies, with 

 one end more pointed than the other, and fituated ur.d>.rthe 

 fliin on each fide of the fpinous procelfes of the caudal verte- 

 bi-x. They approach each other, and touch at their points, 

 which are direfted backwards, and thus produce very com- 

 monly between them the figure of a heart. Theyare co- 

 vered by a llrong denfe white tunic, and their interior ftruc- 

 ture cunfifts of a number of fmall tubes arranged in a radi- 



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ated manner around a vacancy, or canal, which runs nearly 

 in the middle of the gland, into which they all open and 

 difchargc their contents, in the fame way as the tubuli iiri- 

 niferi do into the pelvis of the kidney. The middle canal 

 leads to a papilla on the Ikin of the rump, and termmates in 

 a fimple foramen. It deferves remark, that the tubes towards 

 the circumference of the glands are fo-t and ir.diftinft, and 

 their contents are liquid and pale coloured ; but before their 

 termination, the tubes acquire more firmnefs, are a little fe- 

 parated into packets, their fecretion becomes an opake yellow, 

 and of more confiftence ; thus affording an obvious and 

 interefting view of the change which may be wrought upon 

 fccrcted fluids after their formation, while they are paffing 

 through their glands. The fluid produced by the glands on 

 the rump of birds, although of an unftiious nature, is ftill 

 not pure animal oil. It has more confidence, and is lefs af- 

 fedted by heat ; which properties it principally acquires in 

 the ends of the tubes, before they open into the common 

 duift, as already mentioned. It is, howe\-er, fufficiently 

 oleaginous to prevent the adhefion of moifture to the furfacc 

 of the feathers. When birds make ufe of it, they turn 

 their head round to the rump, and comprefs the glands with 

 the bill, when a quantity of oily matter exfudes, with which 

 they belmear their feathers, arranging the barbs upon their 

 ihafts at the fame time by means of tiie bill. Thefe glands, 

 as m-ght be prcfumed from their life, are particularly large 

 in x\\e /"Mimming birds. Sre Plated, in ih.c Anatomy of Eirdj. 

 Fig. 5. (hews the oil glands of the duck of their natural fize : 

 a a the two glands ; b b their foramina on the papilla, into 

 each of which a briftlc is introduced; cc the iiitegumsnts 

 reflected on each fide to bring the glands into view. Fig. 6. 

 of the fame plate is a feition of one of the oil gl?.nds fome- 

 what magnified ; a the canal in the centre into which the ra- 

 diated tubes open ; bb the external portion of the tubes ; cc th« 

 interior extremities more dillin£t, and of a deeper colour. 

 Organ of Sinell. 



The fhape and fituation of the noflrils are ufed by natu- 

 raliils as clalufic charafters of birds; and, therefore do not 

 require particular confideration here. They confiil of two 

 flits, varying in the length and width, commonly placed on 

 each fide beliind the bafe of the bill. There are no mufcles 

 provided for dilating and contracting their aperture, as ia 

 mammalia. 



The interior of the organ of fmell is formed by a feptum 

 and three turbinated bodies, over which the pituitary mem^ 

 brane is fpread. 



The fuperior turbinatum aflumes in general the fliape of a 

 bell ; it is formed of cartilage, and is attached to the 01 

 frontis and lacrymale ; it is hollow within, and divided by a 

 flight prominence into two apartments, which are continued 

 for a little way in a tubular form ; the external ends by a 

 blind extremity behind the middle turbinatum ; the internal 

 opens into the cavity of the nofe. The fuperior turbinatum 

 is fmall in the pafflres and galiine, fomewhat larger in the 

 fcanfores, increafes in bulk in the accipitres, and ftill more in 

 the anferes, and in the gralU it is grcatell of all. Accord- 

 ing to the obfervations of Scarpa, the acutenefs of fmell is 

 fixaftly proportioned to the magnitude of this part of the or- 

 gan, as it is upon it only and the feptum that the olfaftory 

 nerve is fpread. 



Tiie middle lurbinalum has been likened by Scarpa to a cu- 

 curbitc. It is connedted on the external part to the cartila- 

 ginous pinna of the nares and the bony procefs of the upper 

 jaw, and inferiorly it is attached to the cartilaginous feptum 

 of the nofe. It is compofed of a cartilaginous lamina, 

 which in the goofe makes two folds and an half; but in 

 the gralU it is coroprefled, and forms only oae tura and an 

 3 K 2 halfi 



