MiliTllKltN clIlMyKliA. 



insi 



more iimnciliate funtiiiu;itiou oi' tlie iMtcral liiu' proiun' 

 consists lit' :i siil)()rbhMl lir.-mcli", i-uiiiiiii_u' iilili(iiK'l\- 

 downwards and forwards aloiio- the posterior margin of 

 each orliit and tlience obli([nely upwards and forwards 

 idong the sidiorliital margin, t(_) a point about twice as 

 far from the tip of tlie snout as from the eye, wliere it 

 forms an iS'-sliaped curve', first downwards and liaek- 

 wards'', then downwards and forwards, afterwards join- 

 ing tile supraorl)ital braneii, just before the junction of 

 the latter witli the con-esponding canal on the other side- 

 of the bodv. Where the suboi'bital bi-aneh first alters 

 its course, <in the cheek, below the low(>r posterior cor- 

 ner of tlu' orbit, it sends out a branch downwards and 

 backwards, an opercular canaT, which becomes narrower 

 and narrower until it disappears externalh', being con- 

 tinued, howe\er. by a row of narroAv, transversel)' set, 

 sharp-edged jiort'S, rigiit across the branchiostegal mem- 

 brane. Just before the origin of the opercular branch 

 from the suborl)ital, the latter sends out another branch 

 in a downward direction, a malar canal', which soon 

 forks into a maxillar-s' and a mandibular' canal. The 

 former runs along the cheek, below the middle thereof, 

 to a line with the anterior margin of the nostril, where 

 it divides into two branches, an upper anterior (maxillo- 

 rostral'O and a lower posterior (maxillo-nasal''). Each 

 of the last-mentioned canals crosses the under surface of 

 the snout to meet and join the corresponding canal on 

 the opposite side of the body; but the maxillo-rostral 

 branch also sends out, upwards and torwai-ds, in the 

 median line of this under surface, an unpaired canal', 

 which unites it to the above-mentioned junction between 

 the supraorbital branches. The mandibular branch cross- 

 es over behind the lower jaw in the same maimer as 

 the opercular branch across the isthmus. All these ra- 

 mifications of the canals belonging to the system of the 

 lateral line mark the head and in particular the snout 

 with an extremely singular design, all the more striking 

 as their anterior parts, on the cheeks and snout, become 



coarser, with more distinct fissure, and at certain |ioints 

 are widcMied an<l deepened, thus aci|uiriiig a moniliform 

 ap])earance. lietweeii the dilatations the inside of the 

 canal is ])ierce(l by the inward ramifications of the c.ucal 

 ducts described by Costa-'. In addition to these canals 

 appertaining to the true system of the lateral line the 

 snout is furnished with the numerous muciferous sacs 

 (ampulhe) described by Lkvdk;'. From the many pores 

 that partly follow, in single rows, the above-mentioned 

 canals and the sharp fohl which the skin forms in a 

 cur\e just before the no>trils and abo\ e the lateral por- 

 tion of the njiper lip, partly are scattered, in groups or 

 more isolated positions, between the said canals, these 

 long ampulhe take their origin, in the form of ducts 

 directed ui)wards and forwards (as the\- ap|)roa(-h the 

 very tip of the snout, backwards). Tlie posterior am- 

 pulhe terminate ca'cally under the skin, betwe('ii it and 

 the large fibrous cai)sule, filled with a gelatinous mass, 

 that occupies the interior of the snout, resting on the 

 cartilaginous rods which we liave observed above in the 

 rostral region of the Iloloccpliali. The anterior ampulhe 

 on the under surface of the snout, as well as the above- 

 mentioned ducts issuing from the anterior parts of the 

 branches of the lateral line, penetrate within the said 

 cajjsule. Ill the gelatinous mass are also embedded the 

 large and numerous ramifications of the fifth pair of 

 cranial nerves', which innervate the ampullar The 

 skin itself is marked on the l)ack of the snout with 

 a network (thimble-like |)attern) of pits, and within 

 each of these may be seen in miniature the same 

 rotiforin figure as we remarked above in the dermal 

 covering that invests the muciferous sacs of the Stur- 

 geons. 



The mouth is comparatively small. It presents, in 

 combination with the large preoral nostrils, an appearance 

 seldom exemplified in the preceding fishes. The dermal 

 fold which bounds in front both the mouth and the 

 nostrils has a great reseml)lance, it is true, to the lower 



" Orbital and suborbital canals, according to Garman. 



' In Plate XLyi, fig. 3 of the present work tlicre is an error, tliis branch being connected with the supraorbital canal. 

 ' Jtiijutar canal, according to Garmak. 



'' Sometimes the opercular and malar branches issue in a comnion canal {orbitonasal, according to Garman) from the suborbital branch. 

 ' Angular canal, according to Garman. 

 ■^ Oral canal, 



' Subrostral canal, .. .. „ 



'' Nasal canal, ., „ 



' Median canal, ,, ,, „ 



■* Fna Regn. Nap., Pesci, Chimceroidei, tav. VII, figs. 1 — 4. 

 ^' Arch. Anat., Physiol. 1851, p. 253, taf. X, fig. 1. 



' According to Ewart, to whose investigations we shall return below, the nerves wliieh innervate both the ampulL-c and tiie other parts 

 of the cephalic system of the lateral line are homologous with an anterior division of the nervus facialis of the higher vertebrates. 



