540 



into a stem, and sends off brandies ; that 

 there is also a root is evident, which, how- 

 ever, we now know is merely the organ of 

 attachment, affording no nourishment to the 

 animal. Most of the Polypi form compound 

 animals, attached to one another by lateral 

 appendages, or by their posterior extremity, 

 participating in a common life, while at the 

 same time they enjoy their individual and in- 

 dependent existence. In reference to the dif- 

 ferent views which have been entertained on 

 this once questionable subject, Mr. Broderip 

 makes the following just observation: "Bor- 

 rowing from Aristotle and Pliny the term 

 Polypus, by them applied to a cephalapod, 

 the systematic naturalists who followed 

 Linnaeus collected under this title many 

 really animalized masses in the form of 

 plants, and after abundant examinations by 

 Ellis and others, of the membranous, horny, 

 or stony ' fulcra,' bases, or axes, which remain 

 after desiccation or decay of the softer parts, 

 generally agreed in opinion that to all these 

 plant-like bodies were associated active 

 living animals like the Hydrse described by 

 Trembley. As in a tree the flowering and 

 reproductive organs manifest more active 

 and varied functions than the general mass 

 of bark and wood which serves to unite 

 them in one common life, so in these Zoo- 

 phyta the little Polypi expanding from their 

 cells for food, light, or aeration, and shrink- 

 ing back upon the agitation of the water, or 

 withdrawal of the light, seemed like so 

 many animal flowers, which might be stu- 

 died apart from the Polypiaria which they 

 adorned. They were in fact studied apart, 

 and unfortunately attention was more di- 

 rected to the wonderful permanent fabric, 



for this portion of the Zoophytic division of 

 the animal kingdom, and many of the er- 

 roneous generalizations and hypotheses re- 

 garding the lower forms of animal life." 



POLYPTERUS. This is a fish, which is 

 usually about eighteen inches in length, and 

 partakes in some degree both of the osseous 

 and cartilaginous kinds, but seems most 

 nearly allied to those species of the genus 

 Esox which are furnished with large, strong, 

 and bony scales. Its shape is elongated and 

 nearly cylindrical : its head is defended by 

 large bony pieces or plates, and the body 

 covered with large and strong scales, very 

 closely affixed to the skin : the pectoral fins 

 are placed immediately beyond the head ; the 

 ventral at a vast distance beyond it, the abdo- 

 men in this fish beingof averyunusual length; 

 the anal fin is seated very near the tail ; 

 and the tail is of a rounded or ovate form. 

 At a small distance beyond the head, along 

 the whole length of the back, runs a con- 

 tinued series of small dorsal fins, varying in 

 different individuals from sixteen to eighteen: 

 each of these fins is of an ovate shape, up- 

 right, or but very slightly inclining back- 

 wards, and is furnished with a very strong 

 spine at its base, while the remaining part 

 consists of four or five soft and branched rays, 

 connected by their united membrane. The 



or ' Polypidom,' as Lamouroux calls it, than 

 to the Polypi themselves. Hence the im- 

 perfection of all the schemes of classification 



I lateral line runs nearly straight from the 

 I gill-covers to the tail : the eyes are small 

 and round ; the mouth of moderate width ; 

 a row of small and sharp teeth in each jaw ; 

 and the upper lip furnished with a pair of 

 small and short tentacula at its tip. This 

 fish inhabits the depths of the Nile, remain 

 ing among the soft mud, which it is thought 

 to quit only at particular seasons, and is 

 sometimes taken in the fishermen's nets at 

 the time of the river's decrease. Its colour 

 is sea-green, paler or whitish on the abdomen, 

 which is marked by some irregular black 

 spots. It is called by the Egyptians Eichir, 

 and is said to be one of the best of the 

 Nilotic fishes for the table. 



POLYTHALAMIA. The name given 

 by Ehrenberg to minute calcareous-shelled 

 many-chambered Mollusca, both recent and 

 fossil. They are also called Forumtnifura 

 by D'Orbigny. [See INFUSORIA.] 



POMFRET. (Stromateus.) A genus of 

 Acanthopterygious fishes, having the same 

 compressed form as the Dory (Zeus"), and the 

 same smooth epidermis ; but the muzzle is 

 blunt, and not retractile. It has a single 

 dorsal, and a few concealed spines anteriorly, 

 but 110 vcntrals. The vertical tins ore thick- 



uu) 



ened as in the scaly-finned fishes ; the gullet 

 has a number of spines attached to the 

 membrane. They are found in the Medi- 

 terranean, the Indian Ocean, and Pacific. 

 Some of the species differ considerably in 

 form. The one here represented is the 

 Black Pomfret (Stromateus niger). 



POMOTIS. A genus of fish, belonging to 

 the I'ercidcc family. The Northern Pomo- 

 tis (Pomotis vuiyaris) frequents the shel- 

 tered inlets of Lake Huron and the ponds in 

 that vicinity, concealing itself, in the sum- 

 mer time, beneath the broad leaves of the 

 nuphar and water-lily, where it may be 

 readily taken with a hook baited with a 

 small fish or worm. The form of this fish 



a broad oval, the anterior apex rather 

 acute, and formed by the lower jaw, which 

 projects slightly beyond the upper one. It 

 is about eight or nine inches long ; the body 

 is much compressed ; the scales adhere firmly 

 to the skin and are rather large ; the head is 

 small, and the opposing surfaces of both 

 mandibles are covered with small teeth 

 crowded closely together. The branchios- 

 tegous rays are considerably curved ; and 

 the caudal fin is slightly sinuated at the 

 extremity with rounded lobes. Its principal 

 food is small Crustacea. 



