popular JBictumarn nf 8m'matcrj feature. 701 



rowed, denticulated on the inner margin, 

 rounded anteriorly, truncated posteriorly j 

 hinge with four oblong, compressed, di- 

 verging teeth in one valve, receiving between 

 their grooved sides two similar teeth in the 

 other j in each valve two muscular impres- 

 sions. The inside is of a brilliant pearly 

 texture, tinged with purple or golden brown. 

 The Tri<i<>i<!u /x't-tiiurfn was formerly so very 

 rare, that even an old worn-out valve would 

 fetch a high price. The fossil species are 

 numerous, and occur in the upper and lower 

 oolites, the lias, and in the beds of green 

 sand. 



TRIGONOCEPIIALTTS. A genus of poi- 

 sonous serpents, characterized by having the 

 tail terminated by a horny conical process 

 or spur. They are closely allied to the Rat- 

 tlesnakes. 



TRILOBITES. These Crustacea, which, 

 as Cuvier tells us, appear to have been an- 

 nihilated during the ancient revolutions of 

 our planet, are denned in that most scientific 

 work of Dr. BurmtMer's, devoted to their 

 history, were a peculiar family of Crustacea 

 nearly allied to the existing i'hi/llt'txjda, ap- 

 proaching this family most nearly in the ge- 

 nus BranrhiiHin, and forming* link connect- 

 ing the riii/llofxxln with the 'I'eciliipoda. We 

 need not add that they are only found in a 

 fossil state, and that our figure, which repre- 

 sents the Atxi/ifiim candatiis, a very typical 

 form of the family, will give a general idea 

 of the appearance of this group of animals. 



Our countryman, Edward Lhwyd, curator 

 of the Ashmolean Museum, Oxford, con- 

 siderably more than a century ago, was the 

 first author who wrote on them. Dr. Bur- 

 meister, whose work was translated and 

 published by the Ray Society in 184<>, be- 

 lieves, from a comparison of their structure 

 with recent analogues, that these animals 

 moved only by swimming, and remained 

 close beneath the surface of the water ; they 

 swam in an inverted position, the belly up- 

 wards, and made ue of their power of rolling 

 themselves into a ball as a defence agaim,t 

 attacks from above. Their food was the 

 smaller water-animals. Their habitat was 

 not the open sea, but the vicinity of coasts 

 in shallow water, where they lived grega- 

 riously in vast numbers. Dr. Burmeister 

 believes that the numbers of species could 

 never have been very great, and thinks that 

 some geologists, by judging of size and such 

 characters, have multiplied the species too 

 much. 



TRIMER A. The first section of the order 

 HOMOPTERA, which corresponds with the 



Linnxan genus Cicada, and comprises the 

 most numerous portion of the order, con- 

 sisting of the largest and most beautiful of 

 the species. They are generally saltatorial, 

 but the hind legs are never disproportionably 

 incrassated : they have ordinarily three 

 joints in the tarsi, and very small antennas : 

 the wings are varied in their consistence in 

 ditlorent species, but the upper pair never 

 exhibit two different textures, so remarkable 

 in the lletcroptera. 



TRINOA. A genus of Orallatorlal birds, 

 haying the bill generally not longer than 

 the head, with its tip depressed, and the 

 nasal groove very long. Their toes have no 

 web at the base, and the back toe scarcely 

 reaches the ground. Their legs are shortish, 

 and in general the birds ate of small size. 

 In this genus Is the Sandpiper (TVtaop ca- 

 nutus\ and the Purple Sandpiper (Tringa 

 maritinia.) The Ruffs are closely allied to 

 them. [See RCFF and SANDPIPER.] 



TRITON. A genus of Mollusca, found in 

 the Mediterranean, Indian, and South Seas. 

 The animal has two long tentacula furnished 

 with eyes ; foot round, and generally short. 

 The shell Is oblong, ribbed or tuberculated, 

 with continuous varices placed alternately 

 on each whorl : spire prominent ; right lip 

 often wrinkled, and left occasionally thick- 

 ened, generally denticulated within ; epi- 

 dermis rough ; operculum horny. By some 

 uncivilized nations inhabiting the countries 

 near which it abounds, this shell, often from 

 one to two feet long, is used as a military 

 horn ; the apex having a hole bored in it, 

 notes can be produced by blowing through 

 the aperture, and thus it becomes a rude 

 instrument of music. 



TROCIIILIDJE. A family of extremely 

 diminutive Ti'miirostral birds, celebrated 

 alike for the brilliant lustre of their plumage 

 and the rapidity of their flight. They have 

 a long slender beak, and a tongue split, al- 

 most to its base, into two filaments, which, 

 being capable of protrusion upon the same 

 principle as that of the Woodpeckers, they 

 are said to employ it in sucking up the nectar 

 of flowers : they, however, also feed ou in- 

 sects. They have very small feet, a great 

 tail, and excessively elongated and narrow 

 wings ; balancing themselves in the air by 

 a rapid motion of the latter, now hovering 

 and humming round flowering shrubs and 

 plants, and now darting through the air with 

 almost incredible swiftness. They fight des- 

 perately with each other, and defend their 

 nests with courage. Two of the same species 

 can rarely suck flowers from the same bush 

 without a rencontre : this is abundantly 

 confirmed by Mr. Oosse, when describing the 

 species Trochflns mango. " In the garden 

 were two trees, of the kind called the Malav 

 apple (Eugenia Jfnlaccensin), one of which 

 ] was but a yard or two from my window. 

 The genial influence of the spring rains had 

 covered them with a profusion of beautiful 

 blossoms, each consisting of a multitude of 

 I crimson stamens, with very minute petal?, 

 I like bunches of crimson tassels ; but the 

 1 leaf-buds were but just beginning to open. 



8 o 8 



