306 On the Young of the New-Zealand Astacidae. 



XXVI. — On the Mode in which the Young of the New-Zealand 

 Astacidse attach themselves to the Mother. By J. WOOD- 

 Mason. 



A FEW days ago I received from Dr. Julius von Haast, 

 Director of the Canterbury Museum, a small collection of 

 crustaceans, amongst which is a specimen of remarkable 

 interest. It is a female oi Astacoides zealandicus^ ^ laden with 

 young. On attempting to remove one of these from beneath 

 the tail of the mother, I was surprised to find that it was 

 firmly attached thereto, so firmly, indeed, that I had to exert 

 considerable force in order to detach it, and even then it came 

 away leaving its two hindmost pairs of walking-legs behind. 

 The dactylopodite of each of these legs, on examination under 

 a low power, was found to be provided at its extremity with 

 a strongly hooked, exceedingly acute, movable claw, and on 

 the lower edge at the end with six or seven sharp spines, 

 against which the claw folds, and thus forms a very efficient 

 prehensile arrangement. With these four legs, whicli are at 

 this stage the longest, strongest, and most highly indurated of 

 all the appendages, stretched straight backwards so as to 

 be parallel witli the postabdomen^ the young crayfish hangs 

 suspended head downwards from the postabdominal appen- 

 dages of the mother. The young found thus attached measure, 

 with the postabdomen extended, 1\ millims., exclusive of the 

 antennee. 



The accompanying figure represents the two terminal joints 

 of one of the legs drawn by the aid of the camera lucida. I 

 am not aware whether the young of Astacus JluviatiUs 

 attach themselves in this manner ; certainly Rathke does not 

 state that they do so in his admirable account of the develop- 

 ment of the species. 



Dactylopodite. Propodite. 



The ova in the New-Zealand representatives of the genus 



* = Paranephrops setosus, Hutton, Ann. & Mag. Nat. Hist. 1873, xii. 

 p. 402. 



