loO "TEKUA NOVA" EXPEDITION. 



anal. It suuiiis possible, therefore, that the hackwanl position of tlie (h)r.sal tin of 

 hirval Chipeoids may 1)6 an ancestral feature. 



In Xotoli'jiis (p. 125, PI. I. fiffs. 4, 5), Parab'pis (cf. Pn/iniiofkonits. p. l;;7. PI. \"1I, 

 fi<AS. 1-3), etc., tlic larva lia< a sliorr mit with tin- anus nnt fai- licliiml llie lii-ad ; as 

 the tisli orows the uut liecomes relatively longer, and the anus travels lia<k\vard uiiiil 

 it rcaehes its final position a short distance in front of the anal fin. In a pa])cr on 

 tlie clas.sification of the Inioini (Aim. Mag. N. H. (8) VII. 1911, pp. ll'0-l;5;5) I have 

 pointed out that the long-bodied and long-snouted Parah'/iis is closely rehited to, 

 but more specialized tlian, C/i/orop/ifhahnns. a short-snouted fish of normal jiiscine 

 form. Iiiit with the anus nearer to the liead than tn the anal iiii. It is nnt inipns-^ible 

 that the anterior position of the anus in tlic lar\,d /'itrii/ej>i'< may Ik- due to the 

 e\nhiliiin of tliis genus fi'om a (7ifii)-i'/i/i//i(i/iuu.-<. 



:!. develop:\ient of the fins. 



The pectoral liiis. which arc princi])a|]y concerned with balancing, are usually 

 present in the youngest larvae, and the permanent tin-rays appear at a very early 

 stage. As a rule the caudal, used for propulsion, is the next tin to develop. The 

 hvpurals and iin-rays make their ayipearauce below the notochtml, and then by Hexiou 

 of the latter are brouglit into a terminal position. Afterwards the dorsal and anal 

 rays develop in the eml)rvoiiic tin-told and the pelvic tins grow out. There are many 

 deviations fi-oin and exceptions to the general coinse ot develo[)meiit of the (ins 

 outlined above. 



The dorsal and anal fins nsuall\- (U-iginate in their final position, but in the 

 Clupei(hte, and the ivlated Aliailidae and Fdopidae, they (h-velop more posteriin-ly and 

 tlu' dor.sal espe<-iall\' migrates forwards t'oi- a considerable distance after it has been 

 formed (cf. PI. \', figs. 2-4). In these i'amilies the dorsal tin develops eailier than the 

 anal, but in the liiioiui the reverse is the case (e.g., iSynodus fiynodus, p. 1;!7. PI. \T1, 

 tig. 4; Prymnotlioiins. j). ]:!7. I'l. All. tigs. 1-3). Sometimes the formation of the 

 dorsal tin. or the anterior part ot it. is so delayed that the embryonic fin-fold disappears 

 first; this niav often happen with the spinous dorsal fin of acanthoptcrous fishes (e.g., 

 Odax (laltcatits, p. i4;i,Pl. VIII, tig. 4 ; Trijifcri/^jiun/ r^d-inm, |). 145, PI. IX, tigs. 1,2). 



Notable exceptions to the general rule that the anterior or spinous portion of the 

 dorsal tin develops later than the posterior or soft-rayed jiortion are the Trichiuroids 

 and some Paialichthinae. In the former (e.g., Tkyrsitcs ntiiii. p. 144. PL N'lll.tigs. 1-3) 

 the early formation ol' the spinous dorsal may ])e for purpo.ses of defence, and one may 

 well believe that it would lie effective in warding otf the attacks of the predaceous 

 \oung of such lishes as /'oiiidtdiint.'^ saltdfur (cf Agassiz and Whitman, Mem. 3Iu.s. 

 Conip. Zool. XIV. No. I. 18S5. \k \i\). 



In some l''hti -lishes (jT the sub-tainily r,iralii-ht hinae (e.g., .[iicy/o/tsetfti. [). IK!, 

 ri. I.\. Hti'S. 3, 4) the anterior dorsal ravs are Ibimed at a verv earlv staae and "tow 



