53 



vertcbrcT> in back bone, no ribs and no developed jaws, no 

 limb-fins ; gills in separate sacks on sides of body. 

 Family Petromyzontid^, Lampreys. 

 Petromyzon Jluviatilis, Linn. (Day, vol. IL, p. 350, pi. 

 CLXXXIX.). Silver lamprey. 



B.— Series showing the Reproductive Organs, the Spawn, 

 and the young stages in the development and life- 

 history of some fishes from the Egg onwards. 



B. I. Series of Ovaries and Testes (bard and soft roe). 



1. Ovaries (hard roe) of mature whiting {Gadiis 



merlangus) . 



2. Testes (soft roe) of mature whiting. 



3. Ovaries (hard roe) of mature haddock {Gadus 



(Eglefinus). 



4. Testes (soft roe) of mature haddock. 



5. Ovaries of mature herring {Clupea harengus). 



6. Testes of mature herring. 



7. Ovary and oviducts of skate {Eaia bat is). 



8. Dissection of plaice {Pleuronectes 2)latessa) show- 



ing immature reproductive organs. 



9. Dissection of plaice showing mature repro- 



ductive organs. 



B. II. Series of Mature Ovarian Eggs. 



1. Eggs from the ovary of cod {Gadus viorrhua). 



2. ,, ,, whiting {G. merlangus). 



3. ,, ,, haddock {G. (Eglefinus). 



4. ,, ,, hake {Merluccius vulgaris). 



5. ,, ,, grey gurnard {Trigla gur- 



nardus). 



