43 



EXPLANATION OF PLATE III. 



Fig. 1. One of the branchiae of a Squilla. with parallel tubes. 



Fig. 2. A parallel tube, with a number of smaller tubes coming from it. 



Fig. 3. One of the tubes from fig. 2, more highly magnified. 



Fig. 4. Branchial cavity of a common crab, Cancer pagurus. 



a. Branchiae. 



b. Flabellum. 



Fig. 5. One of the flabella situated on the lower part of branchiae. 



Fig. 6. Flabellum from between the two rows of branchiae. 



Fig. 7. Branchia of the Cancer pagurus, natural size. 



Fig. 8. Two of the conjoined lamellae of the preceding preparation. 



a. The spines. 

 Fig. 9. Hairs from the same. 

 Fig. 10. Branchia of the same crab magnified 175 diameters. 



a. The spines. 

 Fig. 11. Portion of a flabellum magnified 175 diameters. 

 Figs. 12, 13, 14, 15, 16, 17, 18. Hairs from the flabella of various small crabs. 

 Fig. 19. Portion of a hair from the flabellum of the common crab, shewing two rows 



of spines. 

 Fig. 20. A transverse section of the same. 

 Fig. 21. Ordinary hair of the Crustacea. 



EXPLANATION OF PLATE IV. 



Fig. 1 . The branchial organs of the common lobster, showing the branchia c, a, 



and the flabella b, b. 

 Fig. 2. Branchia of the lobster, natural size, with the free extremities of the tubes 



shown. 

 Fig. 3. Branchia of the same lobster, showing the points of attachment of the tubes. 

 Fig. 4. Branchia and flabellum attached. 

 Fig. 5. A portion of a branchia magnified 175 diameters. 

 Fig. 6. A similar preparation seen edgeways. 

 Fig. 7. A transverse section of a branchia. 

 Fig. 8. One of the tubes highly magnified. 

 Fig. 9. Flabellum of a lobster. 

 Fig. 10. Flabellum of a large cray-fish. 

 Fig. 1 1. Portion of fig. 9 magnified 175 diameters. 

 Figs. 12, 13, 14. Hairs from the flabellum of a lobster. 

 Fig. 15. Hair from the tail of an ordinary lobster. 

 Figs. 16 & 17. Hairs from the flabella of the large cray-fish. 



