450 Mr. C. Spence Bate on the British Diastylidse. 



recent observations by Prof. Agassiz, communicated by him to 

 the author, the Cuma are in part, if not always, the young or 

 immature forms of certain Macroura, as Alphceus, Palamon, and 

 Hippolyte. This distinguished observer has actually obtained 

 Curme from the eggs of Crangon septemspinosus, Palcemon vul- 

 garis, and Hippoli/te aculeata.^' 



A communication made by so eminent a man is like the 

 sound of a trumpet, the voice of which extends to the farthest 

 limits of the earth, and long is the time ere its echo shall cease 

 to be repeated. 



Agassiz says that he has " actually obtained Cumce from the 

 eggs of MacrouraJ' This strong assertion by so great a man 

 will require the clearest evidence that careful investigation can 

 produce in order to demonstrate its error and to elucidate the 

 truth, that the Cumce are adult animals perfect in themselves, and 

 that they belong to the suborder Stomapoda among Crustacea, 

 in which they form a family of themselves, the Diastylida>. 



I have chosen this name from the earliest given to a genus of 

 the family, which appears moreover to be the type of the group ; 

 also as considering the term Diastylis to be more significant in 

 relation to the form of the animal than either of the other 

 generic names in the family. 



Kroyer, in his illustrations to the 'Voyages en Scandinavie,^ &c., 

 has figured several species most carefully and most correctly, in 

 accordance with the usual practice of that eminent carcinologist. 

 More recently Mr. Goodsir, in the Edinburgh New Philosophical 

 Journal for 1843 (in a paper which has been reprinted in full in 

 BelFs ' British Crustacea ^), has described all the known British 

 forms, and with the exception of Kroyer, whose work Mr. Goodsir 

 appears not to have been aware of, has entered more fully into 

 the subject than any previous author. He has recognized their 

 true character as animals in their adult condition, and considers 

 that they should be ranged with the lower forms of Macroura, 

 and between them and the Stomapoda. With this. Prof. Bell in 

 his ' British Crustacea ' entirely agrees, and has included these 

 anomalous forms of Sessile-eyed Crustacea amongst the Podoph- 

 thalma. 



Sir James Balyell, in his fine work on the ' Bare Animals of 

 Scotland,^ has figured one or more species, without adding much, 

 we believe, to the knowledge of either the structure or habits of 

 the animals. 



The first step will therefore be to describe the separate parts 

 of the dismembered animal ; and although this to a certain extent 

 has been done by Kroyer, yet his great work is in the hands of 

 so few, that it will scarcely be deemed a work of supererogation 

 even to repeat some that he has well displayed, and by this 



