P R I 



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PRO 



the term primary will, in all probability, 

 yield to that proposed by Mr. Lyell, 

 namely, hypogene. 



PRIMO'RDIAL. (from primordium, Lat 

 primordial, Fr.) Original ; existing from 

 the beginning ; first in order. 



PRISM, (arpio-jwa, Gr. prisme, Fr. prisma, 

 It.) A solid figure, the ends whereof 

 are parallel, equal, and similar plane 

 figures, and the sides which connect the 

 ends are parallelograms. Prisms take 

 particular names from the figure of their 

 bases or ends, namely, triangular, square, 

 rectangular, pentagonal, hexagonal, &c. 



PROBOSCIDIA'NA. A family of quadrupeds 

 belonging to the order Pachydermata. 

 The proboscideans have five toes to each ; 

 foot ; they possess no canine teeth, but 

 two tusks, which project from the mouth, 

 and frequently attain to an immense size. 

 The nostrils are continued out into a 

 proboscis, which is exceedingly flexible, 

 possesses great flexibility, and terminates 

 in a finger-like appendage. The pro- 

 boscis may be considered as the hand of 

 the elephant. One living genus only of 

 this family is known, namely, the ele- 

 phant ; the other genus, the mastodon, is 

 believed to be extinct. 



PROBO'SCIS. (Trpo/Scxriaf, Gr. from /36<r/ew, 

 to feed, and vrpo, before, proboscis, Lat. 

 proboscide, Fr. proboscide, It.) A 

 lengthened tube, snout, or trunk belong- 

 ing to certain animals. The proboscis of 

 the elephant is of great length, serving 

 the purposes of a hand, conveying to the 

 mouth anything it desires to swallow. 

 It is an instrument of most delicate 

 touch, of scent, and breathing, and of 

 prehension as adroit as that of a hand. 

 By the extraordinary flexibility with 

 which it is endowed, it can not only be 

 inflected inwards to carry things to the 

 mouth, but be bent upwards, downwards, or 

 laterally, to lay hold of things above, below, 

 or on either side ; and, by the assistance 

 of its finger-like termination, it can grasp 

 anything, even the most minute, as 

 readily as we can with our four fingers 

 and thumb. In insects, when the in- 

 strument for suction extends for some 

 length from the mouth, it is called a pro- 

 boscis ; such is the apparatus of the butter- 

 fly, the moth, the gnat, the house-fly, and 

 other insects that subsist on fluid aliment. 



PROCU'MBENT. (procumbens, Lat.) Lying 

 down ; prone. In botany, a term applied 

 to plants, the stems of which lie or fall 

 upon the ground through weakness. 



PRODU'CTA. An extinct genus of equila- 

 teral inequivalve, striated bivalves. It is 

 found in the mountain limestone and 

 older secondary rocks only ; it is allied to 

 the existing genus Terebratula. 



PRO'LEGS. The name given to what are 



termed the spurious legs of insects. While 

 the number of the true legs is limited 

 to six, the prolegs are often very nu- 

 merous ; they consist of fleshy and re- 

 tractile tubercles. The true legs are 

 generally protracted by horny scales ; but 

 the coverings of the prolegs are wholly 

 membranous. The office of the prolegs 

 appears to be merely to serve as props to 

 support the body while the insect is 

 walking, and to prevent its hinder part 

 from treading on the ground. They are 

 frequently terminated by single or double 

 hooks ; and also by a marginal coronet of 

 recurved spines. Dr. Rogret, Bridg. 

 Treatise. 



PRO'TEUS. (7rpwrV, proteus, Lat.) The 

 name given to a genus of the order Ba- 

 trachia. One species only has been 

 hitherto discovered, namely, the Proteus 

 Anguinus. A subterranean saurian, 

 which never makes its appearance on 

 the earth's surface, but is always con- 

 cealed at a considerable depth below it, 

 being found in subterraneous lakes and 

 caves two or three hundred feet below 

 the surface of the ground. The following 

 particulars are extracted from Sir H. 

 Davy's Consolations in Travel : " Inde- 

 pendently of the natural beauties found 

 in Illyria, and the various sources of 

 amusement which a traveller fond of 

 natural history may find in this region, it 

 has a peculiar object of interest in the 

 extraordinary animals which are found in 

 the bottom of its subterraneous cavities, 

 namely, the Proteus anguinus, a far 

 greater wonder of nature than any of 

 those which the Baron Valvasor detailed 

 to the Royal Society a century and a half 

 ago, as belonging to Carniola. 



At first view, you might suppose this 

 animal to be a lizard, but it has the mo- 

 tions of a fish. Its head, and the lower 

 parts of its body, and its tail, bear a 

 strong resemblance to those of the eel ; 

 but it has no fins ; and its curious bron- 

 chial organs are not like the gills of 

 fishes ; they form a singular vascular 

 structure, almost like a crest, round the 

 throat, which may be removed without 

 occasioning the death of the animal, who 

 is likewise furnished with lungs. With 

 this double apparatus for supplying air to 

 the blood, it can either live below or 

 above the water. Its fore feet resemble 

 hands, but they have only three claws or 

 fingers, and are too feeble to be of use in 

 grasping or supporting the weight of the 

 animal ; the hinder feet have only two 

 claws or toes, and in the larger specimens 

 are found so imperfect as to be almost 

 obliterated. It has small points instead 

 of eyes, as if to preserve the analogy of 

 nature. It is of a fleshy whiteness or 



