]\[TOLOGY OF FISHES. 211 



superficial mxisclc, arising" i'rom tlie temiinal aponeurosis of the 

 'lateral nuiscle,' cxpaiuls and separates i'an-wise, fig. 131, z, to its 

 insertion into the bases of the caudal rays. Tlie deeper-seated 

 lascicles are ex])osed l)y tlic removal of the foregoing and tlicir 

 ajioneurotic origin, and arise from the coalesced terminal centrums 

 oi the caudal vcrtehra;, to l)e inserted further from the basal joints 

 of tlie rays, and more advantageousiy ibr effecting tlie movements 

 wliich alter the spread of the tail-fin. Slender longitudinal mus- 

 cles, suj)ra-cariii,ulcs, extend along the mid-line of tlie Ijack from 

 the occiput to the first dorsal, and along the interspaces of the 

 dorsal fins in the Cod : similar muscles, fig. 1.31, u, extend from 

 the hist dorsal to the caudal fin in the Perch ; and infrn-cdri- 

 iialcs, ib. V, extend from the anal to the caudal along the keel of 

 the tail. In the Gymnotus the su])ra-carlnales form a single pair, 

 which extends from the occij)ut to the end of the tail. The modi- 

 fied cranio-dermal spines, which constitute the oval sucking-disc 

 of the Remora, \vx\e a complex series of minute muscles, which 

 raise or depress the transverse lattice-work ; and thus become tlve 

 means of giving the little feeble fish all the advantage of the i"apid 

 course of the whale or the ship to which it may have attached 

 itself. The muscular and membranous webs of the coalesced jjec- 

 torals and ventrals of the Lump-fish, form a sucker on the opjio- 

 site surtirce of the body, by which it may safely anchor itself to the 

 rock, in the midst of the turbident surf or storm-tossed breaker. 



There are many modifications of the muscular system in the 

 orders at the two extremes of the class. 



The segmental disposition of the muscular masses is most 

 simple, most distinct, most like the annulose type, in the Cijdo- 

 stomi : yet it is considerably specialised for the due working of 

 the suctorial apparatus. In the Lamprey, fig. 138, slips are con- 

 tinued or derived from the anterior part of the myocommas, for 

 drawing back, bending in different directions, and ex])anding the 

 mouth. Of these, the superior, e, is inserted into the cartilage, 

 fig. 24, 20 ; raises and fixes it, giving a fulcrum and favourable 

 direction tor the muscle, fig. 138, h, which directly retracts and 

 raises the sucker, a: the inferior slip,/, is inserted into the pro- 

 cess, fig. 24, (J, and into the lower border of the gristly l)ase of the 

 sucker, ib. 22 : it retracts and depresses the sucker. An interme- 

 diate lateral slip, inserted a little higher upon the margin oi' q, fig. 

 24, retracts and draws outward the sucker. All these retractors, 

 co-operating, serve to expand the sucker ; or, if duly antagonised 

 by the spli.iiicter oris, pull back the object seized by the sucker, or 

 draw tlie body of the fish towards it, according to the fixed jtoint. 



P 2 



