THE ANNALS 



AND 



MAGAZINE OF NATURAL HLSTOHY. 



No. 91. OCTOBER 1844. 



XXVIL— C^on the Development of Star-fishes^. By M. SARsf. 



[With a Plate.] 

 Ax unexpected delay having attended the publication of the above 

 work^ in which my observations upon the present subject 'odll 

 appear in full, I propose in the mean time to give the substantial 

 results of my investigations upon the development of Echinaster 

 sanguinolentusX {Asterias sanguinolenta, O. F. Miiller §), and As- 

 teracanthion M'uUeri, a new species closely allied to A. glacialis\\. 



1st. Tlie AsteriadcB possess male and female organs of genera- 

 tion separate upon distinct individuals. The period of propaga- 

 tion commences in the spring, and is eifected by means of ova, 

 which make their appearance in the vesicles of Purkinje and the 

 spot or cell of Wagner contained within these. (PI. III. figs. 3 — 6.) 

 These ova are developed gi-adually ^^^tllin the ovaria, and arc gi\'en 

 birth to by several broods at distinct intervals of time, becoming 

 probably (for this point has not yet been positively ascertained) 

 detached from the ovaria, and after falling into the cavity of the 

 body, reach the ventral surface of the animal by means of special 

 apertures. 



[^Observation. — Tlie ova being thus gradually extruded, explains 

 why they are found within the o^ary of such very different stages 

 of development (PI. III. figs. 4, 5), that young as well as ova are 

 met with in the uterine cavity of the mother.] 



* Eeing a fragment from a work entitled ' Beitriigen zur Fauna von 

 Norwegcn.' 



t From Wiegmann's Archiv, Part 2, 1814. Communicated by A. Tulk, 

 M.R.C.S. 



X Joh. Miiller observes, that this species is undoubtedly the same as the 

 E. Sarsii of Miiller and Troschel. ^. sanguinolenta proves to be the E. se- 

 positus of the same authors. Three Asteriadcs of this colour occur in the 

 Northern Seas. 



§ Cribella oculata of British authors : see Forbes's British Star-fishes, 

 p. 100. 



II I am not at present authorized in extending such statements to other 

 Star-fishes, as it appears indeed that generation is one of those functions of 

 animal life which is subject to most variation even among the lesser groups 

 of allied beings. 



Ann. b^ Mag. N, Hist. Vol.nv. R 



