SIPIIONIXA. 



[ 695 ] 



SKIN 



spores formed in the u link "-cells, uniting 

 toovther and forming a perfect miniature 

 net before escaping from the parent cell. 



See also Pv nur\i. 



SIPHONI'NA, Keuss. A low form of 

 Planorbulina, having open-mouthed tubes 

 leading off the pseudopods from the cham- 

 bers, and large-necked septal orifices. Re- 

 cent and fossil in the Mediterranean area. 

 (Parker and Jones, Ann. N. If. 3. xi. 94.) 



SIPHONOPH'ORA, Koch. A genus of 

 Aphidie. Species numerous, on a variety of 

 plants. S. rosce = Aphis r. (Buckton, Aphi- 

 d<e, i. 104.) 



SH'HONOPH'ORA. An Order of Hy- 

 dro-medusae ; the oceanic Hydrozoa. (Hux- 

 ley, Phil. Tr. 1849.) 



SI PHONOS 'TOM A (Parasite, orPrecilo- 

 poda). An Order of Crustacea. 



Char. Body often almost entirely enclosed 

 in a buckler, consisting generally of one, 

 sometimes of two pieces ; mouth suctorial ; 

 legs formed for walking or prehension, or 

 partly branchiferous and fitted for swim- 

 ming. Parasitic upon fishes, &c. 



These animals (PL 19. figs. 7, 23, 24, 36, 

 and PL 20. fig. 1), which often present the 

 most extraordinary forms, are found mostly 

 affixed to the gills of fishes by means of 

 hooks, arms, or suckers, arising from or 

 consisting of modified foot-jaws. In some, 

 the cephalothorax is distinct from the abdo- 

 men, and the head is more or less distinct 

 from the thorax ; whilst in others the body 

 presents more of a worm-like form, is occa- 

 sionally ringed or segmented, and sometimes 

 exhibits simple or branched lateral lobes or 

 processes. The antennas are mostly rudi- 

 mentary. Flattened elytriform dorsal ap- 

 pendages are sometimes present. The ros- 

 trum is conical, tubular, and furnished with 

 two setaceous or styliform mandibles. The 

 alimentary canal is straight, without a 

 gastric expansion, and its orifices at the two 

 ends of the body. In some, branchial plates 

 form the respiratory organs; but in most 

 the same office is performed by the skin. 



The sexes are distinct, although they are 

 not known in all the species. The males 

 are smaller than the females. The ova are 

 often attached to the lower part of the body 

 of the females, either contained in external 

 ovaries, or simply glued together by the 

 secretion from a special gland, and forming 

 long, cylindrical, straight or convolute ap- 

 pendages. The young animals have but few 

 legs, swim freely, and frequently resemble 

 the young of Cyclops. 



BIBL. Baird, Br. Entomostr. ; M.-Ed- 

 wards, Hist. Nat. Crust, iu.; Siebold, Very I. 

 An. 



SIROC'ROCIS, Kiitz. Probably the 

 mycelium of a fungus. 



BIBL. Kiitzing, Sp. Ah/, p. 153. 



SI ROGO'N I UM, K iitzing. 8. notabile = 

 Mesocat-pus notabilis, Hass. ; S. sticticum = 

 Spirogyra (Zt/ynema, Hassall) stictica; S. 

 breviarticulatum = Spirogyra curvata. 



SIROSl'PHON, Kiitz. A genus of Os- 

 cillatoriaceae (Confervoid Algae), which 

 should perhaps have been placed under the 

 older name of Hassallia. This genus is 

 principally distinguished by the solitary 

 branches passing off from the sides of the 

 rather rigid filaments, the branches arising 

 from longitudinal division and lateral growth 

 of interstitial cells. The plants are black, 

 and found on wet moors, rocks, &c. Two 

 species seem to be established S. ocellata 

 (PI. 8. fig. 12), and S. compacta ; Leigh- 

 ton places the latter among the Lichens ; 

 others appear doubtful. 



BIBL. Hassall, Alg. 231; Kiitzing, Sp. 

 Alg. 315, and Tab. Pkyc. ; Leighton, Lich. 

 Fl 9 ; Rabenhorst, Alg. ii. 285. 



SKELETON LARVA. The larva of 

 Corethra plumicornis, a dipterous insect, of 

 the family Tipulidae. 



It is very transparent, and shows well the 

 internal structure. 



BIBL. Westwood, Insects, ii. 515 ; Prit- 

 chard, Micr. lllustr. 50. 



SKELETONS 'MA, Grev. A genus of 

 Diatomaceae. 



& Barbadense, in the Barbadoes deposit. 

 (Grev. Micr. Tr. 1865, 43.) 



SKIN OB INTEGUMENT OF ANIMALS. 



Three parts are distinguishable in the skin : 

 an outer or cellular, forming the epidermis ; 

 an inner fibrous, or cutis vera ; and an inter- 

 nal or subjacent, known as the subcutaneous 

 cellular tissue. The two former constitute 

 the skin proper. 



The cutis vera or corium (fig. 641 c) con- 

 sists of connective and elastic tissue, with 

 fat-cells, blood-vessels, nerves, absorbents, 

 and unstriated muscular fibres. The fibres 

 of the connective tissue are variously inter- 

 laced and united into interwoven bundles, 

 forming a tolerably dense and firm tissue, 

 with small areolas, and sometimes presenting 

 laminae. The elastic, tissue is less abundant 

 than the connective, and consists of net- 

 works of finer or coarser fibres. 



The outer surface of the cutis gives off 

 a number of conical processes or papillae 



