ACTINOMETRA PERONU. 217 



and von Troschel respectively, and I find that Müller's 

 work may be carried a stage farther. 



The Bonn sjjecimen and a spirit one from Peron's voyage 

 differ very considerably frorn the Retzian type. This re- 

 sembles one of Peron's dry specimens and also that of Quoy 

 and Gaimard from the Moluccas in having but two joints 

 in the secondary and tertiary arms , though there are three 

 joints in the primary arms. In the Bonn specimen on 

 the other hand , and in one from Peron's voyage there are 

 three joints in the secondary and tertiary as well as in 

 the primary arms. But in both types the axillaries are 

 always syzygial or double joints as mentioned by Muller, 

 this being probably the cause which led him to unite them , 

 and at the same time to separate them from Lamarck's 

 other specimen which has no syzygies in the axillary joints 

 (C. multijida). 



The Leyden specimen which I have described above re- 

 sembles that at Bonn and its fellow at Paris in having three 

 joints in all the arm-divisions , and I have called it Act. Pe- 

 ro7m, the Paris example of the type having been obtained 

 in 1803 by Peron and Lesueur. 



This type is very similar to Act. Bennetti but differs in 

 having fewer cirrhi, and in the joints composing them 

 being tolerably uniform in size. The arm -joints too are 

 relatively shorter, while both the first and the subsequent 

 syzygial intervals are longer than in Act. Bennetti', and 

 the pinnules which have stouter and shorter joints are more 

 clothed with perisome. 



This specimen was the host of a Myzostoma which will 

 be described by Professor Graff. 



Notes from tlae Leyden IMuseum, Vol. III. 



14 



