REPORT ON THE CIRRIPEDIA. 9 



The supracesophageal ganglion is well-developed ; in one of the specimens two nerves 

 were indistinctly visible starting from the ganglion and directed towards the antennae; 

 if my observation be correct there can be little doubt that these are the antennal nerves. 

 I have not observed the commissures which unite the supracesophageal ganglion with 

 the thoracic ganglion; the latter is large and oval, and probably only represents the 

 first larger ganglion of the . thoracic chain of Lepas. Neither the small eye near the 

 supracesophageal ganglion nor the large compound eyes at the base of the antennas 

 are present ; the pigment which is so richly distributed over all the organs and parts 

 of Lepas australis is totally wanting in the male Cypris of Scalpellum. This no 

 doubt finds its explanation in the circumstances under which the little animal is destined 



to live. 



Of great importance is the fact that the dorsal invagination, which, as we have seen, 

 causes the division of the body of Lepas into a capitulum and a peduncle, is totally 

 lost in the metamorphosis of the Cypris of the male of Scalpellum ; hence there is no 

 trace of this division to be observed in the full-grown males. This want of a peduncle, 

 together with the smallness of the orifice of the mantle and the total absence of valves, 

 form the most characteristic features of the male in question. 



The metamorphosis of the Cypris-larva, in its latest stage (as figured), into the full- 

 orown male, is now, I think, easy to understand. In this respect at least it quite 

 corresponds to the metamorphosis of Lepas. The difference between the latest stage of 

 the Cypris of Lepas australis and the young Cirriped of that species is not greater, nor 

 less either, I think, than that between the attached Cypris of Scalpellum regium and 

 the young male ; to say that the complemental male of Scalpellum is in its Cypris stage, 

 or thereabouts, is not in accordance with the facts. 



The valves of the Cypris are first of all shed. The cells of the mantle or sack soon 

 develop a distinct membrane of chitin at their surface, which no doubt is as efficient a 

 protection as the shell was, but which contains no carbonate of lime and therefore is not 

 so brittle. When the wall of the male is quite intact, its impenetrability makes it 

 absolutely unfit for transference from absolute alcohol into oil of cloves ; the alcohol leaves 

 the little body faster than the oil enters it, whence the body-wall becomes shrivelled. 

 As the internal structure is best studied in a specimen placed in oil of cloves, and as for its 

 investigation by transverse sections the passing through oil of cloves was also necessary, 

 I found it very useful, when the specimens were quite sound, to make a little opening m 

 the wall before transferring them into the oil. For the rest, this internal structure is 

 very simple. The antennas and the very delicate thorax with the legs are the only parts 

 which show that the little body belongs to an articulate animal ; the whole interior of 

 the body is filled with a mass of connective tissue with very wide meshes, serving to 

 keep the different organs in their places. 



(ZOOL. CHALL. EXP.— PART XXVIII.— 1884.) Ee 2 



