876 Mr. C. Spence Bate on the [Mar. 9, 



and importance of hereditary elements are incapable of being studied 

 and appreciated. 



Through Dr. Carpenter he received from Mr. Power an offer of a con- 

 siderable number of larvae of exotic species, together with the parents 

 from which they had been obtained ; in relation to which Mr. Power 

 wrote : — 



" Deab. Sib, — I have to thank you for your kindness in answering my 

 letter to Dr. Carpenter, and for the memoirs. 



" My collection of Crustacea and the microscope-slides of the larvae 

 are at present, and have been, packed up in Eort Louis. Now I am 

 again on detachment ; and if left here in peace for a few months, I shall 

 arrange my specimens and finish up the microscopic drawings. 



" All my larvae are hatched in basins (the only kind of aquaria my 

 nomad life allows me to use), so each crab or prawn &c. whose larvae I 

 possess is identified with its young ; and this reminds me that on reading 

 Fritz Miiller's paper in the ' Annals ' (1864, vol. xiv. p. 104), I was 

 much astonished, as none of the prawns or prawn-allies whose young I 

 have hatched show any such Nauplius form as shown in figures 1 & 3, 

 &c. ; but all I have observed as yet are born like fig. 8, or near it. 



" I have been quite unable to rear any crab-larvae beyond a day or 

 two after birth ; whether they require moving water or not I do not 

 know ; but certainly, though I have kept the parents alive for several 

 weeks in basins (the water changed once or twice in 24 hours) of salt 

 water, the same method would not succeed with the larvae. I then 

 tried small aquaria, and signally failed again. 



" I have not been in the neighbourhood of fresh water as yet, so have 

 had no opportunities of observing the freshwater Crustacea, though 

 there are a good many crab and shrimp forms. I have found two 

 kinds of that curious parasitic crustacean which adheres like a little poly- 

 pus, a mere bag with a peduncle, but containing hundreds of young 

 Crustacea whose genus I do not know, as I cannot find any account of 

 them in Van der Hoeven's ' Zoology ' *. 



" If I succeed in getting posted to one of the regiments here, my 

 life will be more stationary, and I shall have far better chances of working 

 my crab-hatchings. 



" In Fritz Miiller's paper before referred to, I fancy that he has not 

 hatched the different larvae mentioned. After reading the paper very 

 carefully, I could not help fancying that the various stages of develop- 

 ment were not hatched through, but specimens were captured at different 

 times, and perhaps larvae of totally different species have been given as stages 

 of the same animal. I say this with great doubt ; but reading the paper 

 will, I think, bring every one to the same conclusion. Thus he says, ' the 

 unaltered Nauplius form, probably the same in which the animal escapes 



[* New genus allied to Sacculina, which hatch larvae in the cirriped pupa stage. — 

 C. S. B.] 



