CLASS OF CRUSTACEA. 453 



a series of observations of the same nature on the young of 

 the balanus balanoides, which are recorded above, it will 

 now be seen that this question is already decided, viz., that 

 the balani must undergo two changes of form, or perhaps 

 more, before arriving at a state of maturity. 



* We will now proceed to give a short description of the 

 larva of this species. 



' When viewed from above, the body of the animal is found 

 to be pyriform, with the anterior edge rounded, and the pos- 

 terior extremity ending by means of a point. The whole 

 body consists of three segments : the first forms the greater 

 part of the body ; the two last are minute. Two long un- 

 articulated extremities project from the anterior edge on either 

 side of the mesial line, arising, apparently, from the abdominal 

 surface of the body. Two short antennae arise also from this 

 edge, immediately on each side of the above-described extre- 

 mities. 



' The eye is situated a little behind the anterior edge, and in 

 the mesial line of the body. 



' Two very strong thick legs arise from each side of this 

 first segment of the body. These are bipartite, each division 

 arising from a pedicle common to both, which consists of 

 three segments. The divisions themselves are apparently un- 

 articulated, but are armed with a number of very strong spines. 



' The second segment of the body is minute. The third 

 and last is also minute and pointed, and is armed with three 

 strong spines, which are bent to one side (the left side), that 

 nearest the right side being the shortest. 



' All of these larvje swim after the manner of the rnono- 

 culi, by short and sudden jerks. They propel themselves by 

 means of the two pairs ot' spined extremities. The tail is 

 also in constant motion.' H. G., in E. P. Journal. 



" By the minute and prolonged study of the metamorphoses 

 of animals, we thus prove that these so-called imperfect forms, 

 or forms in transitu, are the permanent forms of adult extinct 

 and recent animal beings. Thus we upset the theory of the 

 transmutation of species, and creation of new forms ; for these 

 forms are embraced in the embryonic, and require but time 

 and circumstances for their full development : nevertheless, I 

 willingly concede to my esteemed friend, M. Valenciennes, 

 that the naturalist is only interested in adult forms, these 

 being the highest specializations to which animals attain : it 

 holds even in man himself."* R. K.] 



* See my Manual of Artistic Anatomy. Kenshaw, London. 



