. The illustrated natural history [microform]. Reptiles; Fishes; Mollusks; Natural history; Reptiles; Poissons; Mollusques; Sciences naturelles. THE PYROSOMA. 441 The curious Boltenia, so called aft(ir Dr. Boltcn, a naturalist, of Hamburg, is found ill mtlier deep waters, being sometimes drawn up by fishermen's linos from a depth of sevt'iity fathoms. The animals of this genus are attached to long footstalks, at the end of which the creature sways like a fritillary on its slender stalk. The two orifices by which walpr is admitted into and ejected from the system are seen, and their remarkable
. The illustrated natural history [microform]. Reptiles; Fishes; Mollusks; Natural history; Reptiles; Poissons; Mollusques; Sciences naturelles. THE PYROSOMA. 441 The curious Boltenia, so called aft(ir Dr. Boltcn, a naturalist, of Hamburg, is found ill mtlier deep waters, being sometimes drawn up by fishermen's linos from a depth of sevt'iity fathoms. The animals of this genus are attached to long footstalks, at the end of which the creature sways like a fritillary on its slender stalk. The two orifices by which walpr is admitted into and ejected from the system are seen, and their remarkable four- cleft openings are well displayed. When very young, the Boltenia is often found affixed to the stem of its parent. We now arrive at the Social Ascidians, two examples of which are given in the ilhistration. The Clavellina may be seen lying upon the leaf of the laminaria, the diftVront individuals being united by long filaments. The blood circulates through tlieso channels of connnunication, passing to and fro through separate tubes. It is a small creatnre, and extremely transparent, the latter characteristic making it a valuable species to tlie physiologist, who is enabled to watch its structure, and the methods in which the (lift'cvent organs i)crform their duties, without needing to dissect it. The Clavellina may be fonnd on the English shores at low water, adherent to rocks, stones, or seaweed, to which it attaches itself by means of the tiny root-like projections which are developed honi the outer tunic, something like the little rootlets by which ivy clings to a wall. OuE second example is the Ryntetiiys, another British species, which is seen affixed tn the stone on the right hand of the illustration, spreading tlower-like from a small base. When full grown, a group of those creatures forms a largish mass, nearly six inches in diameter, and as many in height, each member of the group being about two inches long. They are rather transparent and of a greenish colour,
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Keywords: ., bookcentury1800, booksubj, booksubjectfishes, booksubjectmollusks
