250 



THE CEPHALOPHG U. 



^221. 



of the body, numerous fasciculated plumose, or dendritic branchiae/^ 

 With the Cjclobranchia, and some of the Inferobranchia, the lamelli- 

 form branchiae are situated on the furrow which separates the border of 

 the mantle from the foot,'''' under the form of a continuous cord, or of two 

 lateral rows. 



With the Scutibranchia, the two pectinal rows, which are wholly con- 

 cealed in the cavity of the mantle, have, nevertheless, a certain symmetry ® 

 which is wholly absent with the other Gasteropoda. Thus, all the Tecti- 

 branchia have only a single lamellate or pinnate branchia situated on the 

 right side, rarely on the left, and which is more or less covered and some- 

 times wholly concealed by a fold of the mantle.'^' The Pectinibranchia 

 and Tubulibranchia have a pinnate or pectinate branchia, contained in 

 a cavity which is situated upon the anterior portion of the back and often 

 provided with a siphon on its left side.'^^''' 



With many Nudibranchia, the returning blood from the branchiae is 

 emptied by several veins into the simple auricle of the heart, which (the 

 heart) is situated upon the middle line of the back.<"> With only a 

 few Grasteropoda, as also with the Cirribranchia, Cyclobranchia, and Scuti- 

 branchia, the branchial veins are united into two trunks which open into 

 the simple or double auricle. '^-^ With the other Gasteropoda, which have 

 an uneven, lateral branchia, '^''^ the blood passes from this last, through a 

 short, simple, venous trunk, to the heart situated near its base. 



II. Lungs. 



§ 221. 



The pulmonary cavity, formed in the mantle of the Pulmonata, is situated 



6 With ScyHaea, there are, on the back, two 

 pairs of cutaneous loljes, between and which are 

 numerous branchial vessels. With Glaucus, there 

 are, upon the sides of the body, three pairs of pro- 

 longations which have long, digitiform branchial 

 filaments. With Tfietis, the back ia surrounded 

 by a double row of semi-pinnate branchiae ; while 

 ■with Tritonia, there is on each of its sides a single 

 row of multiramose branchial tufts. With Doris, 

 and Polycera, there are twenty to twenty-flve 

 more or less ramified branchiae, arranged circu- 

 larly around the arms, and capable, from contrac- 

 tion, of being withdrawn into the mantle. 



7 The branchial lamellae form a complete circle 

 ■with Patella, Chiton, and Phyllidia, and two 

 lateral rows with Diphyllidia. 



8 With Fissurella, and Emarginula, there is a 

 row of branchiae on each side of the cavity of the 

 mantle, while, with Haliotis, there are two rows 

 on the left side. 



With Umbrella, Pleurobranchaea, and Pleu- 

 Tohranchus, this branchia, situated on the right 

 Bide and half exposed, is easily seen. On the same 

 side also is situated the branchial lamella often deep- 

 ly concealed between the folds of the mantle, of Gas- 

 teropleron, Apli/sia, liuUaea, Notarchus, &c. 

 liut with Doridium, the branchia is on the left 

 Bide and quite behind. 



Ancylus, which differs from the other Infero- 

 liranchia by its simple branchia, has, moreover, 

 this peculiarity, that this organ has the form of a 

 simple cutaneous enlargement on the left side, con- 



* [ § 220, note 10.] See also Leydig, loc. cit. 

 for the branchiae and their intimate structure, 

 with Paludina. According to this observer, they 



cealed under a fold of the mantle (Treviranus, 

 loc. cit. p. 192, Taf. XVII. fig. 1, 2, d., or Fo^t, 

 loc. cit. p. 28, Taf. II. fig. 1-3, p.). 



10 With Valvata, there is a single pinnate 

 branchia which projects out of a cavity in which it 

 is contained (Gruithuisen, Nov. Act. Acad. Nat. 

 Cur. X. p. 441, Tab. XXXVIII. fig. 2, 3, 5, 12). 

 The branchia is simple and pectinate with f^erme- 

 tus (Philippi, Enumer. Mollusc. Sicil. I. p. 169, 

 Tab. IX. fig. 24), Rostella, and Struthiolaria. 

 It is bi-pectinate with Turbo, and Janthina, and 

 tri-pectinate with Paludina. With many Pectini- 

 branchia, as, for examples, with Harpa, Cassis, 

 Conus, Buccimim, Terebra, Murex, f-'oluta, 

 Oliva, &€., there is, beside a very large unipecti- 

 nate branchia, another organ of this kind which is 

 smaller and bi-pectinate. The epithelium, which 

 covers not only the branchia, but also the walls of 

 the respiratory cavity, plays an important part in 

 the renewal of the water in the branchial cavity, 

 which takes place through its opening, or by the 

 siphon of these Gasteropoda which is situated upon 

 the neck usually a little to the left side.* 



11 Sc.ytlaea, Thetis, Doris. 



12 Tritonia, Dentalium, Patella, Chiton, 

 Haliotis, Fissurella and Emar/^iniila. Among 

 the Inferobranchia, Phyllidia should also be 

 cited here. But with Diphyllidia, on the contrary, 

 the veins appear to pass each into the auricle of the 

 heart. 



13 The Tubulibranchia and Pectinibranchia. 



are unipectinate with Paludina vivipara, and not 

 tri-pectinate, as above mentioned of this genus in 

 general. — Ed. 



