49 



In ast year's proceedings an illustration was given of one of the 

 rarer Copepoda, Monstrilla Anglica. The interesting feature of this 

 was that it was carrying the extruded ova, a condition seldom met 

 with. The specimen did not produce a very satisfactory illustration, as 

 it was dead when found. 



Although the Monstrillidoe are rare, several were found in the tow 

 net used off Bournemouth Pier in the months of April and May. In 

 April Monstrilla Anglica was prevalent, but none carrying ova were 

 obtained. In May, as these disappeared, a few of the other British 

 species, Thaumaleus Claparedii, were obtained. Among these was one 

 carrying extruded ova. As this was alive and vigorous, a much better 

 mount of it could be made, and this has been very satisfactorily 

 photographed by Dr. Dixon. The actual size is about 3-32 of an inch. 



The frontispiece of th« present volume of proceedings is from a 

 photograph of a series of ecdyses of the common shore crab, Carcinus 

 Mcenas. This series is now in the society's museum. 



Dates and (approximate) measurement of the ecdyses taken across 

 the greatest breadth of Carapace. 









Millimetres. 







Millimetres. 



Sept. 



16, 



1902 



... 1.5 



July 10, 



1903 



... 6.75 



Oct. 



16 



5 j 



.... i-75 



Aug. 1 





.. 9 



Nov. 



6 





••• 3 



„ 28 





•• 13 



Dec. 



2 





- 375 



Oct. 9 





.. 15.50 



Jan. 



10, 



1903 



... 4 



Nov. 17 





.. 21.50 



Feb. 



26 





• •• 4.75 



Feb. 12, 



1904 



• • 29.50 



April 



12 





... 5.25 



May 19 





35-25 



May 



9 



>> 



... 6 



Sept. 14 





• • 4!-50 



June 



10 





... 650 



July 15. 



1905 



.. 49 died 



This series represents the growth from what is known as the first 

 Megalopa stage to the full grown crab. 



The previous stages to the Megalopa are known as Zocea, and bear 

 little resemblance to the adult crab. The larva leaves the egg in the 

 Protozcea stage, and almost immediately casts its delicate skin, emerging 

 as a Zocea. 



There are four Zocea stages recognized, produced by successive 

 moulting. At the fourth moult a much more crab-like animal emerges 

 — the Megalopa, and it is from this stage that the series commences. 



H. J. Waddington. 



D 



