. Lake Superior [microform] : its physical character, vegetation and animals, compared with those of other and similar regions . Natural history; Sciences naturelles. . I) M f 8. 34G LAKE SUPERIOR. soinotimes porceivcd only after rcnioviii[j; tlio invcstin;:; inembrano. Tlic opert'ulmn is siibtnaii^ular and lar;^i', wlicu we consider that the upjicr and lifndcr niarj^ins jiass from one to the other by a curve; the lower niaririn is strai,:j;ht and obrKjuc, and as long as the anterior margin is high. The suhojicreuluin is arched on its Avhole circiun- ference, and makes a })r(;j('etion beyo
. Lake Superior [microform] : its physical character, vegetation and animals, compared with those of other and similar regions . Natural history; Sciences naturelles. . I) M f 8. 34G LAKE SUPERIOR. soinotimes porceivcd only after rcnioviii[j; tlio invcstin;:; inembrano. Tlic opert'ulmn is siibtnaii^ular and lar;^i', wlicu we consider that the upjicr and lifndcr niarj^ins jiass from one to the other by a curve; the lower niaririn is strai,:j;ht and obrKjuc, and as long as the anterior margin is high. The suhojicreuluin is arched on its Avhole circiun- ference, and makes a })r(;j('etion beyond the opercuUun. Tho interoiiercubim, ahnost conijiletcly covered by tho iireojiereubnn, presents externally only a small triangular surface, and a small nar- row liand below the lower l)ranch of the preoperculum ; though in reality, this bone is as long as the suboperculum, but less broad, having the form of a very acute triangle, of which the summit would be oq the anterior side. The branchial openings arc very ample, and join each other at tho lower surface of the head. 'I'he branchiostegal membrane, whose offico it is to sliut this fissure conjointly with the opercular apj)aratus, is proportionally lilLle dcvel(»]ied ; it contains commonly nine, some- times ten very crowded, flattened and almost straight rays. Tlie scales are of middle size in proportion to that of the fish. Tho largest are situated beneath the belly, the smallest under the throat, the thoracic belt and the caudal region. Those of the lateral lino are somewhat smaller than those of the adjacent rows. 'J'heirfortn is generall}^ subcircular or iri-egularly (quadrangular, but their verti- cal diameter has a slight tendency to surpass the longitudinal diame- ter. This peculiarity is especially striking on the abdominal region, where really the scales are oblong and of a height sensibly greater than tlu'ir length; at the same time that their outlines become more regular and nearly oval. Their imbrication has e
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Keywords: ., bookcentury1800, booksubjectnaturalhistory, booksubjectsciencesn
