BOTOM08TOHATA. 



KXTtiMOSTKACA. 



oolumella flattened, HpiAing iu a point ulteriorly ; right lip sharp- 

 edged, often thickened and furrowed internally, or strongly armed 

 autoriorly with a oonical point. Operculum horny, demicircular, the 

 summit poiterior. 



The form U widely distributed, but the number of European spe- 

 cie* is very (mall ; the greatest development takes place iu warm seas, 

 where the ipecie* are inont abundant, particularly in South America. 

 The larger proportion of the species of this genus are littoral The 

 true Purpura hare been found at depths ranging from the surface to 

 25 fathoms, and the division which forms the genus Monoctroi, 

 generally on rocks, at depth* ranging from the surface to 7 fathoms. 



De Bhunville states that there are 50 living species of ordinary 

 Purpura, of which four only belong to the French seas. The species 

 of .Woiiorrroj he state* to be five, all from South America. Deshayee, 

 in 1m Tables, give* 76 as the number of living species of the genus 

 Purpura (Lam.), and 6 as that of the living species of Monoctrot. 

 Dr. Lea state* that his cabinet has nine. Hr. Broderip describes 

 two new species, and Mr. Powys one, from Mr. Cuming's collection 

 (Port St Elena, Valparaiso, and Maldon Island, in the Pacific), and 

 Mr. Broderip another, Pur/iura Gravmi. figured under the name of 

 .l/rr.r eariniferut, in Mr. Sowerby's ' Conchological Illustrations.' 

 (' ZooL Proc.') Mr. Sowcrby describes nine species of Monoctrot, 

 among them .V. pundulatum (Gray), from Mr. Cuming's collection. 

 Woodward puts down the species at 140. 



De Blainville divides the species into four sections: 1st Those 

 whose right lip, near the notch, is armed with a conical horn, or tooth, 

 which is pointed, and more or less curved. This section U the genus 

 itmoceroi (De Montfort), the animal of which, according to M. Rang 

 and others, differs in nothing from that of the other Purpune. 2nd. 

 The Bucciuoid Purpurir, whose lip is without a tooth, and whose 

 aperture is moderately widened. Purpura Lapillut (liuccinum 

 Lap ill iu. Linn.), for example. (See above, Jluccinum.) 3rd. The 

 Patulous Purpura, also without a tooth at the lip, and whose aperture 

 is very wide : Purpura Pertica for instance. 4th. The ventricose 

 tuberculated specie*, of which he gives P. neritoidei as the type. 

 M. Rang divides the species into two groups only. The first, consisting 

 of those which have the right lip simple, or only furrowed internally : 

 the second, of those whose right lip U always thickened and armed 

 anteriorly with a conical point. 



Example of the first, Purpyra Ptrrica. Locality, East Indian seas. 



Example of the second, Purpura imbricata (Monoceroi imbricatum, 

 Lam.). Locality, South America. 



Furfur* imkrirala {ilonarrroi imbrifalum. Lam.). 



Potnl Purpura. De Blainville itate* ('Malacologie') that no foasil 

 pecie* of Monoetrot were then known. Dexhayes, in hi* Tables, records 

 one (tertiary) from Italy. Dr. Lea describes and figures three new 

 foaril specie* from the Tertiary of Claiborne, Alabama (Eocene of Lyell). 

 Of the ordinary Purpurir De Blainville state* that there are nine foanl 

 (pecie*, one of which is the analogue of P. Lapillia (liutrinum Lapillut, 

 Linn.), *o common on our coast*, a* well a* those of France. Deshayes, 

 in hi* Table*, give* the number of fossil (tertiary) specie* as four, of 

 which be record* one, P. kirmattoma, a* both living and fossil. Wood- 

 ward state* the fo**U species to be thirty. 



I'atalloid Enlomottoma ; that is, one whose shell i* very large 

 in it* totality, very flattened, with a spire but little marked, and 

 without a columella. 



CmcMtpai. De Blainville speaks of the animal as entirely un- 

 known ; but according to Lemon it resemble* that of Purpura. Shell 

 thick, rude, and wrinkled transversely on it* external surface : spire 

 very small, hardly -projecting ; aperture oval, very large, notched 

 anteriorly, where there are two dentiform appendage* ; no columella ; 

 DiuKuIar improwion of a horse-shoe shape, and very visible. Oper- 

 culum horny, transparent, trapezoidal, concentric, with a marginal 



South America is the locality of Concholfptu. It is very abundant 

 on the coast* of Peru and Chili, and sometime* attain* to a very 

 large size. 



Cunchntrpat Is only known as a littoral specie*, 



Lamarck first placed Concholfptu near Purpura. fuvii-r itive* it 

 very nearly the same position. M. Rang remarks that lie might have 

 well united the genus to Purpura, after the example of De Ferussac. 

 In fact, be adds, M. Lesson's communication touching the animal 

 which the latter brought home from the South Sea had proved to 

 M. Rang that it differs in nothing from that of Purpura; itsoperculum 

 alone affords a well-defined character. 



There i* but one species known ; but M. Rang states that there are 

 two distinct varieties. 



Ex. C. Peruriana. 



Cancholtpat Frruriana. 



Coneholepa* is not known in a fossil state, properly BO called. It 

 occurs among other species of the coast at considerable elevations 

 above the sea. 



ENTOMO'STRACA (Miiller), Midi Irucctt, for such is the meaning 

 of the term applied to certain Aquatic Animals forming, according to 

 Latreille and others, the second general division of the Crustaceans, 

 and for the most part inhabiting the fresh-water. The brain, or rather 

 the nervous knots which supply its place, consists of one or two globules 

 merely. The heart is in the form of a long vessel. The branchiae, 

 composed of hair-like processes, which are either isolated or connected 

 in a beard-like form, a pectinated shape, or one resembling aigrette*, 

 form a portion of the feet, or of a certain number among them, and 

 sometimes mandibles and the upper jaws. [CYPRIS ; BKANCHIOI'ODA.] 

 The number of the feet varies, and in some of the genera is above a 

 hundred. These feet, ordinarily, are proper for no purpose but 

 swimming; and are sometimes ramified or divided, and sometime* 

 furnished with pinnules, or composed of lamellar joints. Nearly all 

 of them have a shell, consisting of from one to two pieces, very deli- 

 cate, and most frequent ly almost membranous and transparent, or at 

 least a large anterior thoracic segment, often confounded with the 

 head and appearing to replace the shell. The integument* are generally 

 rather horny than calcareous, a condition which, as Latreille remarks, 

 approximate* the Eutomoxtracaii* to the Insect* and Arachnid 

 those which are provided with ordinary jaws, the inferior or ox ' 

 ones are always uncovered, all the jaw-feet (picds-machoires) perform- 

 ing the office of true feet, and none of them being applied upon the 

 mouth. The second jaws, with the exception of the Phyllopoda, 

 resemble those organs, and Jurine has sometime* designated them 

 under the name of bands. These characters, says Latreille, distinguish 

 the Masticating Entomoitraca (Entomoatraces Broyeurs) from the 

 Afalacott raea ; the other Entomottraca which compose hi* order 

 Paeilopoda- cannot, he says, be confounded with the Malacottrata, 

 because they arc deprived of organs fit for mastication, or because 

 those parts which apjx-ar to perform the office of jaws are not collected 

 anteriorly and preceded by a labrum as in the true Crtutacea and the 

 Masticating Insect* (Insectes Broyeurs), but simply formed by the 

 haunches of the locomotive organs, and furnished, for the purpose of 

 enabling them to execute that office, with small spines. The Pfrcilo- 

 pwln, he observes, represent in this class those of the class of insect* 

 which are denominated Suctorial (Suceurs). They are almost all 

 parasites, and seem to lead us by degrees (par nuances) or shades of 

 ililli mice to the Ltnutai ; but the presence of eyes, the property of 

 moulting or changing the skin, or even of undergoing a metamorphosis, 

 and the faculty of being able to traii>-pi-t ilfi,,;lv from one place 

 to another by means of feet, appear to Latreille to establish a well- 

 defined line of demarcation between the animals last named and the 

 preceding. With regard to the metamorphosis, he remarks, that the 

 young of the Daphnia and of some other nearly allied genera, those 

 probably also of Cyprit and of Cylherina, differ not at all or scarely at 

 all from their parcnta, in point of form, at the time of their exclusion 

 from the egg ; but the young of Cyclop*, of the Phyllopoda, and of 

 Aryuliu, undergo in their infancy remarkable changes, as well in the 

 form of the body an in the number of feet These organs ind< 

 some (in the A ryuli for instance) suffer transformations which modify 

 their use*. The same author state* that he has consulted, relative to 

 these transformations, several well-informed naturalist*, who have had 

 frequent occasion to observe the Lerncea:, and that those observer* 



