661 



BRANCHIOPODA. 



BRANCHIOSTOMA. 



there described and illustrated the gradual development of the 

 embryo, and the metamorphoses which it undergoes from its first 

 production until it arrives at a perfect or adult state. These, he says, 

 will be found to correspond with those of Branchipm, Chirocephdhu, 

 and Apui, animals with which its alliance can no longer be doubtful. 

 A rtemia bears a long journey very well. We have had a glass jar 

 full of them in their native brine sent to London. /They lived a 

 considerable time and were in full life and activity, affording very 

 satisfactory opportunities of observing their habits and of confirming 

 the statements of Mr. Thompson. They are constantly gliding with 

 an even motion in the clear circumambient fluid, sometimes on their 

 backs, sometimes on their sides, sometimes on their bellies, and seem 

 to move with equal facility in every direction. Their transparency 

 and the unwearied undulating motions of their respiratory paddles 

 render them very interesting objects, and convey a deep impression 

 of the harmony of adaptation of members to two such apparently 

 anomalous ends as breathing and locomotion at the same moment. 



The salt-pans at Lymington and some salt lakes in Siberia appear 

 to be the only localities where these animals have been hitherto 

 detected. 



Branchiput stagnalw of Milne-Edwards, Cancer etaynalit of Linnaeus, 

 Gammarus ttagnalia of Fabricius and Herbst, Aput piidformis of 

 Schceffer, who found it in a ditch by the road which leads from 

 Ratisbon to the town of St. Nicholas, Chirocephalu* diapkanus of 

 Prevost, belongs to this division of Latreille. It is a British animal, 

 and is especially known as inhabiting the pools on the road-side of 

 Blackheath Common. [CHIROCEPHALUS.] 



Eranchipiu ttaynalu. 



1, Male, magnified ; a a, composite or network eyes ; b b, antennsc ; t c, mandi- 

 buliform horns ; d, proboscidiform moveable tentacula, rolled spirally ; r, simple 

 rudimentary eye ; //, leaf.like natatory feet or oars ; g, male organs ; h h, tail ; 

 i, terminating filament* ; 2, front view of the head ; 3, tail of the female ; 

 * egg-pouch ; /, female organ; 4, a young BranchijHU after the flri-t moult. 



2. Without a Tail. 



The genus Eulimene, Latreille, belongs to this sub-section. The 

 body is nearly linear, and there are four short antenna; almost filiform, 

 of which the two smallest, which much resemble feelers, are placed at 

 the anterior extremity of the head, which is furnished with two eyes 

 mounted on cylindrical pedicles. The branchial paddles are 11, and 

 immediately behind them is a terminal demi-globose piece in place of 

 a tail, from whence issues a long delicate treadlike process, which may 

 perhaps (according to Latreille) be an oviduct. Eulimene //,//. 

 whose body is for the most part white, with its posterior extremity | 

 black (Artemia Euliment, Leach), the only species described by 

 Latreille, was found in the Mediterranean near Nice. 



Afpidophora. 



Of this last division of the Phyllopa, Latreille says that they have 

 80 pairs of feet, all furnished near their base with a large oval vesicle, 

 the two anterior feet, which are much the largest, resembling antenna?. 

 A large shell or crust covers the larger portion of the upper part of the 

 body. This shell is free, shield-shaped, notched posteriorly, and 

 bearing anteriorly on a circumscribed space three simple sessile eyes, of 

 which the two anterior are largest and lunated. There are two bivalve 

 capsules containing the eggs, and annexed to the eleventh pair of feet. 



Aput produrtiu [BisocuLUs] is an example. Mr. Thompson figures 

 a species, Aput ffuildinyii, from the West Indies, and observes that 

 there appear to be two European species confounded under the 

 specific name cancriformit, namely, Schoeffer's and Dr. Leach's, which 



most resemble Apus Guildingii, and that described by Savigny, in which 

 the elongated shield entirely covers the natatory members. 



Mr. Thompson observes that there is a considerable approximation 

 between Artemis and certain Trilobitcs (Bucephalithus, &c.), nor can 

 there be any doubt that the analogies of Branchipus, SeroHs, and 

 lAmulus all contribute to the illustration of that most ancient race of 

 Crustaceans. [TRILOBITES.] (Burmeister, On the Trilobitet.) 



BRANCHIO'STOMA, the name given by Costa to the most anoma- 

 lous of all living fishes, and indeed of all the Vertebrata. 



This extraordinary animal was first discovered on the coasts of 

 Britain, a single specimen having been sent to Pallas from the coast 

 of Cornwall during the latter part of the last century. The great 

 naturalist of Russia described and figured it in his ' Spicilegia Zoolo- 

 gica ' under the name of Limax lanceolatus, believing it to be a mollusk, 

 though remarking in his description of it on the resemblance of some 

 of its characters to those of a fish. It seems to have been lost sight 

 of for more than half a century, and with the exception of a brief 

 reference in Stewart's ' Elements of Natural History ' we find no notice 

 of it in any synopsis of animals. In 1834 it was re-discovered by 

 Costa on the Neapolitan shores, who described it in the 'Annuario 

 Zoologico ' under the name of Branchiostoma lubricum ; and some 

 years after in his ' Fauna of the Kingdom of Naples ' gave a fuller 

 account of it. Costa first perceived that it was a fish and not an 

 invertebrate animal, and remarked its affinity to the Cyclostomatous 

 fishes. In 1836 Mr. Yarrell gave an account of it in his ' History of 

 British Fishes ' under the name of the Lancelet(.4nipAttnw lanceolatus). 

 He had not then met with Costa's account of it. He figured and 

 described it from a specimen found by Mr. Couch at Polperro in Corn- 

 wall, the first taken in that locality since its original discovery there. 

 Mr. Yarrell gave the first correct notice of the chorda dorsalis and 

 vertebral column. About the same time, singularly enough, consider- 

 ing how long it had escaped notice since the days of Pallas, it was 

 taken by several naturalists on the coasts of Sweden. Lundevall and 

 Loven found it in Bohuslan in 1834, but did not give an account of 

 it till 1841. Retzius had it from the same locality, and published a 

 notice of it in the 'Berlin Proceedings for November, 1 1839, in which 

 also is a communication on the same subject by Professor J. Miiller. 

 Rathke gave an account of its structure in 1841. In the same year 

 Mr. J. Goodsir published an elaborate memoir on its anatomy in the 

 'Transactions 01 the Royal Society of Edinburgh' for 1841, being the 

 result of his examination of two examples taken in the Irish Sea by 

 Professor E. Forbes in 1837. In 1842 a most valuable memoir on this 

 animal was read before the Royal Society of Berlin by Professor J. 

 Muller, and this paper beautifully illustrated appeared in the volume 

 of 'Transactions' of that society published in 1844. 



Besides the Instances of its capture above mentioned it has been 

 since taken by Mr. MacAndrew on the west coast of Scotland, and 

 by Professor Edward Forbes in the jEgean Sea, and by those gentle- 

 men on the south coast of England in 1846. 



The great interest which attaches to this fish depends on the 

 strangeness of its anatomical characters, the unexampled degradation 

 of its organisation among the Vertebrata, and the link which it forms 

 between the highest of animals and some of the lowest. A verte- 

 brated animal without a brain, a fish with the respiratory system of a 

 mollusk, and the circulatory system almost of an Annelide, presents a 

 combination of characters which must excite the wonder and interest 

 equally of the physiologist and the systematic naturalist. Scarcely 

 any animal yet discovered is so likely to change received views of 

 classification and relative order of characters as the Lancelet. As yet 

 however it has attracted but little attention among zoologists, though 

 the physiologists and anatomists have fully perceived its value. For 

 these reasons we shall give a full account of what is now known 

 respecting its external character, structure, and habits. 



The usual size of the Lancelet is about 2 inches in length ; the 

 height to the length being as 1 : 10, and the breadth to the length as 

 | : 10. It is of a lanceolate form tapering to each extremity, and 

 riband-like. Anteriorly it terminates in a head scarcely distinguish- 

 able from the body, apparently pointed, but when examined closely 

 seems to end jn a rounded and somewhat spathulate rostrum, beneath 

 which is the mouth, a longitudinal opening, fringed on each side by a 

 row of long filaments which can close in and clasp alternately, so as 

 to protect the oral opening. Along the back runs a continuous fin, 

 which dilates near the sharp posterior extremity on each side so as to 

 form a sort of caudal fin. Near the tail opens the vent, in front of 

 which is a median fin continued to another opening situated a little 

 behind the centre of the body (porus abdominalis), and serving as an 

 outlet for the genital products. Continued from this forwards nearly 

 to the mouth are two strong lateral folds, mistaken by Pallns for the 

 margins of a ventral disk, and hence leading him to consider the 

 animal a Gasteropodous Mollusk. The entire animal is translucent 

 and of a silvery whiteness, its sides being marked by the indications 

 of the lateral ichthyic muscles, which give it the aspect of a small 

 sand-eel. 



Organisation. Skeleton. The osseous system consists of a chorda 

 dorsalis tapering at both ends, and, strange to say, not presenting .the 

 slightest vestige of a cranium, and of the germs of superior and 

 inferior inter-spioous bones and fin-rays in the most rudimentary 

 state. The chorda dorsalis is composed of from 60 to 70 vertebrae. 



