k 



Mr H. Goodsir on the Sexes of the Cirripeds, S^c. 99 



The eye is large, shining, black, and quadrate. 



The remaining part of the body is pyriform, composed of se- 

 veral segments, and having the two remaining extremities 

 arising from each side of it. The tail consists of two long 

 spines, which arise from each side of one of the last segments 

 of the body. These spines are almost equal in length to the 

 body, and they are strongly serrated on their external edges. 

 The first pair of legs arise from the anterior part of the first 

 segment of the body ; they consist of a peduncle, which is com- 

 posed of two or more segments, and of two separate portions 

 which arise from the peduncle, and which are formed in the 

 same way as those of the former stage. The last pair of legs 

 is also formed in the same way. 



SECTION III. ON THE LARVA OF BALANUS TINTINNABULUM. 



There is no set of animals which has caused greater annoy- 

 ance to systematists than the Cirripeda. 



They were first arranged by Linnaeus, along with the tes- 

 taceous mollusca. Cuvier at first followed this arrangement ; but 

 latterly placed them in a distinct class by themselves between 

 the Mollusca and Articulata. Lamarck, Latreille, M'Leay, 

 and other authors followed this latter arrangement ; the two 

 last authors acknowledging, at the same time, their closer con- 

 nection with the Articulata. 



The decision of this important question, however, was left 

 to our countryman, Mr J. V. Thompson. This gentleman 

 having obtained some minute mussel-like animals, at first con- 

 sidered them to be nondescripts belonging to the Crustaceans, 

 but on a further examination, and by keeping a few of them alive 

 in glass-vessels of sea-water, he was soon enabled to make out 

 their nature and relations satisfactorily. To use Mr Thomp- 

 son's own words — '' They were taken on the 1st of May, and 

 on the night of the eighth the author had the satisfaction to 

 find that two of them had thrown off^ their exuvia, and 

 wonderful to say, were firmly adhering to the bottom of the 

 vessel, and changed into young barnacles. "*" The above men- 

 tioned statements set at rest, in a great measure, the previous 

 discussions as to the position of the Cirripeds in the animal 

 kingdom. 



