406 Dr. F. Miiller on a Ilyhrid Balanns. 



culiim when the hand, for example, is passed between them 

 and the window. 



It is remarkable that individual animals are much shyer, 

 and others, again, bolder than the rest — that the former always 

 remain longer closed, and the latter venture out more quickly, 

 and even become accustomed to the passage of the hand at 

 regular intervals. I may remark, in passing, that I detected 

 similar mental differences between the animals of a group of 

 Eujyomatus Jlorihundus. 



Once when, in repeating these observations, I was watching 

 the action of the cirri in some examples of Balanus armatus 

 which I had taken freshly from Carijoa and cleaned from their 

 coating of sponge, I saw that one of them suddenly ceased strik- 

 ing with its cirri, held them for some seconds immoveable 

 and widely sj)read out, and during this period the penis ex- 

 tended to its utmost length and moved about as if feeling or 

 seeking for something. I then no more disturbed my animals 

 with the shadow of my hand, in order, if possible, to see this 

 spectacle repeated ; and in fact I soon witnessed the same phe- 

 nomenon again, not only in the same animal, but also in three 

 or four others. I now placed these ardent animals close to- 

 gether, in order to facilitate their reciprocal copulation ; but as 

 often as the elongated penis came within reach of the cirri of 

 a neighbour, it was pushed to and fro by them, and the animal 

 did not remain quiet so as to give access to it. Upon this I 

 examined two of the animals, and found the entire canal of 

 the penis densely filled with semen ; but in both there were 

 also ova which had already completed their segmentation, and 

 consequently no longer required fecundation. With the penis 

 so filled, when extended to its utmost length, semen must 

 certainly have been expelled from it (which I could not have 

 seen upon a white saucer) ; but at the same time, from the 

 length of the penis, usually extended in a lateral direction, 

 this semen would be removed from the vortex produced by the 

 cirri of the same animal and placed within reach of neigh- 

 bouring animals which might require it. It is remarkable 

 that, although at that time I made the observation upon four 

 or five animals simultaneously, I have been unable to repeat 

 it, notwithstanding that I have repeatedly looked for it in nu- 

 merous fresh animals. 



The second observation which seems to prove that fecunda- 

 tion sometimes occurs even between different species oi Ba- 

 lanus is as follows : — Among the Balani obtained on Cartjoa, 

 which I had at the fii'st glance determined as B. improvisus^ 

 var. assinnUs, there was one that struck me by a somewhat 

 reddish coloration, such as I had never seen in this infinitely 



