78 Zoology 



The Copepods are represented by 5 genera and 37 species, but it is safe 

 to say that with the possible exception of Wicken Fen the group has 

 hardly been touched. It is certain that a careful investigation of Whittlesea 

 would greatly add to the number of species. Of the recorded species, that 

 of Cyclops gigas Glaus is the most important, since it is the only authentic 

 record in the British Isles. 



The Ostracods are or were till quite recently a sadly neglected group of 

 Crustacea and yet they should be of considerable interest. In Cambridge- 

 shire, the ostracod fauna is remarkable, no less than 32 genera and 65 

 species being recorded. Siphlocandona similis Baird is a rare species, but 

 occurs fairly abundantly on Wicken Fen. The genus is not recorded 

 outside the British Isles. Prioiiocypris olivacea (Brady and Norman) is a 

 rare species, but it was found in large quantities quite recently at Ashwell 

 (in Hertfordshire just outside the County) by P. F. Holmes. The genus 

 Pseudocandona is also recorded from Wicken. This is an important record, 

 for there has probably been more confusion over the species P. pubescens 

 (Koch) than over any other species of freshwater ostracod. 



The sperms of ostracods are the largest among the whole animal 

 kingdom, and moreover they are highly mobile. In many species, and 

 even in many genera, males are unknown and yet in those cases where 

 males do occur the male genital organs are of a highly comphcated type. 

 There is on record one species, Herpetocypris reptans Baird, which was 

 knowTi to breed entirely by parthenogenesis for eleven years. The males 

 of this genus are unknown while the females still retain spermatheca with 

 ducts of relatively enormous length, presumably for the reception of these 

 giant sperms, and yet it is pretty certain that the sperms ceased to exist 

 long before the Tertiary period. Holmes has recorded a second species of 

 Pseudocandona from Lake Windermere which promises to throw a con- 

 siderable amount of light on this obscure subject. 



There is yet another record which should be of great interest. Hemicy- 

 there villosa Sars is recorded from the River Cam, where it is quite abun- 

 dant on occasions. It can be traced right out to sea and is recorded by Sars 

 from some of the deepest fiords of Norway. The same species is also 

 recorded in the fossihsed state from the Pre-tertiary period. 



HIRUDINEA 



W. Ambrose Harding records nine out of the eleven species of British 

 freshwater leeches in the Coimty. The medicinal leech [Hirudo medkinalis) 

 has apparendy disappeared from Cambridgeshire many years ago. Among 

 the more local species, Theromyzon tesselata and Hemiclepsis marginata 



