114 



The various species of Aphis amongst insects are an exception to the 

 general rule, being for the most part ovo-viviparous ; but to this subject I must 

 return by and bye. In the last division, of Oviparous animals, when 

 development of the gcnn takes place out of the body of the parent, either with 

 or without incubation, are to be enumerated all birds, without a single 

 exception, nearly all fish, most batrachia and reptiles, insects, Crustacea, 

 annelida, &c. 



Embryology will form the only true basis of a natural classification. I 

 dare say many here are cognisant of the fonn of that strange frog-like fish, the 

 angler, Lophius piscatorms. This fish was placed by Cuvier amongst a small 

 group of fishes which he designated Pectorales pedicuUs, " having pectoral 

 fins like feet." But this may be, indeed is most likely to be, a thoroughly 

 artificial mode of classification. It never does to select one particular character- 

 istic, though pertaining to a number of animals, as a basis of classification. Fish, 

 "with pectoral fins like feet," comiDrise species having no clear affinities with 

 each other. How does embryology aid us in assigning the frog-fish or angler 

 to its proper place ? Is the Lophius, or angler, a higher development of the 

 Blennies, Gobies, Cottoids, and Scidiyius ? Has it anything whatever to do with 

 them? Agassiz shall answer this question. He says, "Another well-known 

 family of fishes is that of the Lophioides. To this group belongs the Lophius, or 

 goose-fish, with which the Cottoids, or Sculpius, and the Blennioids, with 

 Sources and Anarrhichas, the so-called sea-cat, ought to be associated. It was 

 my good fortune to have an opportunity of studying the development of the 

 Lophius, and to my surprise I found that its embryonic phases included the 

 whole series here alluded to, thus presenting another of those natural scales on 

 which I hope all our scientific classification will be remodelled when we obtain 

 a better knowledge of embryology. The Lophius, in its youngest state, recalls 

 the Tsenioids, being long and compressed ; next, it resembles the Blennioids, 

 and, growing stouter, passes through a stage like Cottus before it assumes the 

 depressed form of Lophivs." 



"What is the relative standing of skates and sharks? Which shall we 

 place highest ? 



"On geological evidence I had placed the skates highest because the sharks 

 precede them in time ; but this fact bad not been established on embryological 

 e'N'idence. Professor Wyman has followed the embryolegy of the skate through 

 all its phases, and has found that in its earlier condition it is slender in outline, 

 with the appearance of a diminutive shark, and that only later it assumes the 

 broad shield-like form and long tapering tail of the skate." 



It is well known that all the various animals on the earth, from lordly 

 man to the humbkst polype, start from the same point. As Huxley has said : 

 "If you trace back to its first germ, a man, or a horse, or a lobster, or an 

 oyster, or any other animal you choose to name, you shall find each and all 

 of these commencing their existence in forma essentially similar to each other ; 



