ORDER F ORAMINIFERA (D'ORBIGNY). FULL OF HOLES. 



129 



SEPIA, or Cuttle-fish. Head surrounded with eight arms and two legs 

 or feelers; body fleshy, depressed, contained in a bag, which is obtuse 

 behind, and furnished with a narrow fin on each side throughout its whole 

 length ; mouth terminal, its mandibles resembling those of a parrot, very 

 large and powerful ; arms furnished with sessile suckers, legs with pedun- 

 culated ones ; within, near the back, is a spongy, calcareous, opaque bone, 

 varying slightly in form in the different species ; and in the abdomen is a 

 bag which contains an inky fluid. 



The type of the genus, S. offidnalis, is abundant in the Atlantic and 

 Mediterranean Seas ; found, but somewhat rarely, in the British and Irish 

 Channels ; the dorsal plate is known by the name of Cuttle-fish bone, and 

 was formerly employed in medicine as an absorbent; the inky fluid of 

 some of the species had been erroneously supposed to be the pigment 

 employed by the Chinese in the composition of Indian Ink. 



The AMMOXITES, or Siiake stones, are found in a fossil state. Septa 

 angulated ; margins undulated, or marked like 

 the leaves of an Acanthus. They are found 

 in beds of the secondary mountains, varying 

 in size from that of a pea to an ordinary- 

 sized cart-wheel. They are subdivided ac- 

 cording to the variations of their whorls and 

 syphon. 



Of this section (Tetrabranchiate), the Pearly 

 Nautilus is an example. (Engraving on p. 128.) 

 In the Pearly Nautilus the mantle, so called by Owen, is attached to the 

 hind part of the head, before passing back to cover the viscera and form 

 the visceral bag, is produced into a large fold, concave posteriorly, over- 

 lapping the involuted convexity of the shell, and sending down on each 

 side a lengthy process, free and unattached, which he considers capable of 

 being expanded over the anterior margins of the shell's mouth. Close to 

 the basal angles of this mantle are the eyes, not sunken, but supported on 

 short pedicles, and thus indicating the position of the head cartilage, their 

 ganglions resting upon its dorsal extremities. 



The skeleton of the Octopus, the largest animal of the Dibranchiate 

 section, is least developed : the head cartilage is of an irregular form, its 



Ammonites. 



Octopus or Poulp. 



middle pierced by the aperture for the gullet ; its hind part contains the 

 so-called brain, and its membranous externally ; and laterally it supports a 

 pair of large ganglions ; in front it is thicker and harder, encloses the 

 remainder of the cesophageal nervous ring and the organs of hearing, and 

 on either side stretches out a plate, which gradually thins and supports the 

 eyes. From the under surface of the cartilage arise eight long muscular 

 arms of a trihedral form, and gradually tapering towards their tip ; upon 

 the base of which are two rows of circular suckers, of various size, and 

 about two hundred and forty to each arm. No contraction indicates the 

 neck, but the visceral bag rises above the head, is large and muscular, and 

 contains a pair of slender styliform cartilages, corresponding to the horny 

 belts of the Pearly Nautilus. In front of the visceral bag and near the 

 head is the aperture of the funnel, which is a perfect tube. The general 



Calamary. 



form of both kinds is lengthy, with a narrowed neck, distinctly separating 

 the head from the visceral bag, which is flattened from before to behind, 

 and the connection between which is so long that the head and neck can be 

 retracted and projected from the bag to a considerable extent. 



In the Calamaries (LoLioo) and Cuttle-Jish (SEPIA), the so-called skeleton 

 acquires a more well-defined form, in connection with the horny pen-shaped 

 organ existing in the hind part of the visceral bag of the former, and the 

 calcareous plate occupying the same 

 portion in the latter. The form of 

 the head cartilage in the Arrow 

 calamary, Loligo sagittata, and in 

 the Common Cuttle-fish, Sepia offid- 

 nalis, is very similar, but in the 

 former is deeper from behind forwards, and in the latter widest from side 

 to side ; in the Cuttle also it is thickest. In shape it resembles a slouched 

 hat without the head, its concavity towards the mouth, and its convexity 

 facing the visceral bag. The number of the arms in both Calamary and 

 Cuttle are four pairs, short in the former, and nearly as long as the body in 

 the latter, their basal surface furnished with a double row of suckers. But 

 besides these, each kind is furnished with a pair of very long arms, of a 

 flattened cylindrical form, and expanding at their tip, each into a lozenge- 

 shaped surface, upon which part only suckers exist. The real use of these 

 long arms is probably to fix the animal, like anchors, to a particular spot, 

 whilst the short arms are employed only hi applying the food to the 

 horny, parrot-like mandibles, which project through the aperture of the 

 circular lip. 



The visceral bag in the Calamaries and Cuttle-fish is of a lengthy form, 

 flattened from behind to before, but more cylindrical in the former; in 

 front it principally consists of a thick muscular structure, but on its 

 posterior surface this is either deficient or very thinly overspreading a 

 shining coat, which lines the whole of its interior cavity : this part of the 

 animal, however, is protected by the existence in the Calamary of a horny 

 body, which, from its resemblance, is called the pen, and, in the Cuttle-fish, 

 of a calcareous structure, called its bone, which was supposed by Spix to 

 be the analogue of the spine of Vertebrate animals ; an opinion long since 

 exploded. Upon the fore part of the neck of the Calamary and Cuttle-fish 

 is situated the funnel already referred to, in shape like a flattened conical 

 tube deprived of its tip, which forms its orifice just above the root of the 

 anterior arms. Its base is received within the front of the wide mouth of 

 the visceral bag, slightly connected to it by the thin external skin, and by 

 the lining membrane ; but more firmly by a pair of cartilaginous ear-like 

 sockets on the front of the base of the funnel, which receive into their 

 cavities a pair of oblong cartilaginous studs, projecting from the correspond- 

 ing surface of the visceral bag. Both are more distinct in the Cuttle-fish 

 than in the Calamar, as might be expected from the great extent of the 

 aperture of the visceral bag in the former than in the latter, and therefore 

 requiring a stronger connection. 



ORDER FORAMINIFERA (D'ORBIGNY). FULL OF HOLES. 

 THIS Order, which was established by M. D'Orbigny, consists of innu- 

 merable minute, foraminated, polythalamous, internal shells, the greater 

 number of which are microscopic. The name given by D'Orbigny to this 

 Order was suggested to him by the circumstance that the cells communicate 

 only by small holes (foramina). These shells exist in myriads on the sea- 

 coasts; they are also found in the chalk or tertiary formations in countless 

 multitudes. In De Blainville's arrangement the families of this order are 

 included among his Cettulada ; but in Owen's both classifications are 

 abandoned ; for that eminent naturalist having made the respiratory system 

 the foundation of his arrangement, was led to reject the Foraminifera from 

 the Molluscous series, because of their deficiency of any trace of Cephalo- 

 podous organization, as well as from the very low position they occupied 

 (when living) in the scale of creation. Hence, in Plate 2, we have indi- 

 cated their doubtful position by a significant sign (?). 



