THE LAMPREY. 7 



m.v), a slender rod, having the form of a T with a very 

 long stem, and situated in the middle line beneath the 

 lingual cartilage, the anterior ends of the two being con- 

 nected by fibrous tissue. 



16. The annular cartilage (Figs, i and 4, an\ a stout 

 circular cartilage, supporting the oral funnel (§ 21), and 

 giving attachment to the maxiUary and mandibular teeth 

 (§ 24). 



17. The styliform cartilages (Fig. i, st\ two 

 elongated, tapering rods, attached by their thickened proxi- 

 mal ends to the posterior edge of the annular cartilage, a 

 little below its middle, and directed backwards and some- 

 what downwards. 



18. The branchial basket (Fig. i, d.c, v.c, a — k, pc), 

 a cartilaginous framework supporting the gills. It consists 

 essentially, on each side, of (i) a longitudinal rod or dorsal 

 cartilage {d.c), springing from the dorsal portion of the para- 

 chordal {h.f), and passing backwards along the side of the 

 notochord ; (2) a second longitudinal rod or ventral 

 cartilage {;v.c), lying, close alongside, and partly fused with, 

 its fellow of the opposite side, in the middle ventral line ; 

 (3) irregular transverse arches {a — g, k) uniting the dorsal 

 and ventral cartilages and passing between the outer gill- 

 clefts ; (4) lateral longitudinal bars (h, i) connecting the 

 transverse arches immediately above and immediately below 

 the gill-clefts; and (5) a cartilage {pc) supporting the 

 posterior and lateral walls of the pericardium. 



Each of the transverse arches, except the first and the eighth or 

 last, consists of seven ■well-marked portions; of these, the first or 

 dorsalmost (a) and the seventh or ventralmost [g) are flattened plates, 

 produced into longer or shorter anterior and posterior processes; the 

 second (b) and sixth (/) are short curved rods ; the third (c) and fifth 

 le) are flattened, and are produced into forvfardly directed processes ; 

 the fourth or middle portion {d) is a curved rod situated immediately 



