Explanation of the Platen. 8" 



CIRRIPEDES. 



''^Plate IX. Fig. 1, Natural size and appearance of the young of the Barnacle 

 (Lepas balauus) when reposing on its side, with its limbs concealed and 

 the valves closed. 



Fig. 2. The same somewhat magnified as seen from above, to show the 

 turgid appearance of the valves, a, an elbow of the anterior members of the 

 animal. /, tail part. 



Fig. 3. Side view of the same more highly magnified, with its limbs pro- 

 truding from the anterior opening of the valves, h, one of the fore feet, its 

 fellow being removed for the sake of clearness ; this member is represented 

 as when naturally exserted by the animal when it wishes to fix itself by 

 means of the sucker c, and claw d, a fourth large basil joint remains 

 concealed by the shell. /, its six pairs of natatory members behind, seen 

 as ready to give a stroke to the water ; t, the bifurcate extremity of the taij. 

 c, one of its peduncled eyes as seen through the shell, x presumed nucleus of 

 future attachment on the dorsum. 



Fig. 4. One of the Eyes detached and more highly magnified. 

 Fig. 5. The bi-articulate tail, more highly magnified ending in two long 

 and two shorter setae t. a, posterior part of the abdomen. 



Fig. 6. One of the posterior or natatory members very highly magnified, a 

 its outer division, b, its inner division ; the rest of these members are exactly 

 similar, and become changed into the six pair of cirri of Triton as exhibited 

 iu Plate X. fig. 1. 

 Fig. 7. Natural size and appearance of the animal after its metamorphosis. 

 Fig. 8. The same magnified, e rudiments of the eyes seen through the 

 large valves of the operculum h. the smaller valves are pointed out by 

 fig. 6. TO the opening or mouth of the valves, permitting the included animal 

 to be seen. 1,2, 3, 4 the valves of the body of the shell, separated by visible 

 sutures, b the marginal projection of the basis. 



Fig. 9. The same seen in profile, with the arms or cirri protruded c. .5, 

 anterior valves of the operculum ; 6, posterior valves. - 1, posterior valve of 

 the basis ; 2, valves nearest the posterior valve ; 3, valves nearest the anterior 

 valve ; 4 anterior valve ; b , basis. 



Fig. 10. One of the cirri more highly magnified, to show that although 

 pluri-articulate, they are as yet without ciliae. 



Fig. 11. A comnunfuU-growu Barnacle of the natural size (Lepas balanus 

 Linn.) with the animal retracted ; the figures of reference point out the 

 corresponding valves iu figure 8. 



Fig. 12. The same in profile, in the act of throwing off its old skin or 

 exuvium c. 

 4 

 Plate X. Fig. 1, the exuvium of Lepas balanus magnified, o oviduct. 1, 2, 3, 

 4, 5, 6 the six pairs of arms, each consisting of two robust basil joints, sup- 

 porting two branches or cirri, which are each composed of numerous arti- 

 culations, ciliate on the opposite edges ; those designated by the first three 

 figures differ considerably from the others in being shorter and more robust, 

 7n, mouth, covered by the first or roost anterior pair of members, b, cast of 

 the body. 



