n96 Mil. K. II. w iini;ii(ii si; (i\ Till; [Apr. 5, 



an increase in tlie .size of the ventral l()l)e readie.s a step towards 

 the externally symmetrical lioujocercal fin; Avhile Amia proceeds 

 furthest of all in the homocercal direction, rerjnirin^ hut one single 

 feature, the po.^sesf^ion of a true urostylo, to attain the homocercal 

 coalition. 



TELE08Tj:i. 



M A L ACQT r EH YCUl. 



I^IoRMYiirs KAXXUMt). (Moriii vridic.) 



In generiil, Movmi/ras provides a t^'pe of hoiiiocercal caudal fin 

 hy no means generalized. The last two or three vertehi-jo are 

 directed slightly upwards. The urostyle is absent or fused com- 

 ])letely with a. hypural bo^ie ; such an advanced homocercal feature 

 a-s this is not cojisistent with the position of Morinyrus as one of 

 the least specialized of Teleost«,a position assigned to it according 

 to general characters. In respect to the hv})urals, inicomnion 

 features are shown : in the first place the last centruin presumably 

 is fused with the last hypural but one, instead of the last as is 

 usual : again, two hypurahs are attached to the penidtimate 

 vertehra and tlie anterior of these is exceptionally large. It is 

 important to notice that only two hypuval bones ;ire associated 

 with the last vertebral segment— the .small nuud)er being another 

 feature of the specialize<l homocercal c;\udal. The epaxial 

 elements are interesting ; the neural arch to the l;ist centrum is 

 strongly developed ; it is pierced throughout by the spinal cord 

 which is continued beyond the arch among the deipiotiichia. It 

 will be remembered that a similar condition of the last neuial arch 

 was found in Amia. The neural arch of the penultimate vertebra 

 is very nnich reduced, and the antepenultimate veitebra bears an 

 epural bone. 



E.NonAiLis Exc'RASicnoLus, (Olupeiche.) 



The Anchovy pi-ovides an illustiation of one of the least speci- 

 alized of homocercal caudal fins. No centra enter into the 

 upturned part of the caudal axis. The notochord is prolonged 

 beyond the long uro.style, hut e.xcept for the extieme end which 

 extends among the dermotrichia, it is protected hy seveial .slender 

 and closely fitting en.shcathing hones which it is diitic-ult to 

 homologize. Dor.sally and ventrally at the end of the notochord 

 is a delicate cjirtilage, each, it may l)e, a vestige of once fmictional 

 n<'ural or ha'inal arches ; such vestiges aie leferred to hy Ky<ler 

 as opisthural cartilages. The hypaxial en{losk(>li'tal supports of 

 the fin-rays aie nine in numher. seven of which helong to the last 

 xcrtchral .segment. it is a little dilllcult to decide whether the 

 tfiiii hypural is coiTec.t for all these supports, as some, at any rate, 

 appear to be ventral caudal railials oidy; however, it will l)e 

 hcttcr for the pjesent to call all of them Iiypurals. This fish 

 poss^cs.ses tlie lai-gest numher of Iiypurals (\iz. suxen) to the last 



