RECENT BRITISH OSTRACODA.. 



381 



"glandules mucosae," constitutes a very considerable portion of the contents of the male 

 carapace. It should be noted that the " bursa copulatrix,^^ as well as the testis, is a 

 double organ, one on each side of the median line. The two bursse lie closely in appo- 

 sition, but are not in organic connexion except at the upper margin, where they are 

 held together by a ligamentous tissue. The postabdominal rami are long and slender, 

 and terminate in two unequal slender claws and a short seta. 

 Length -^4 in., height 3V in. . . 



Notodromas monaclius is generally distributed throughout Britain, occurring often in 

 very great abundance. It seems to delight chiefly in grassy pools, or lakes where there 

 is a profusion of vegetation. Mr. Norman tells me that in sunny weather he has often 

 seen it floating on the surface of the water in considerable numbers. Dr. Baird gives 

 the neighbourhood of London and Hugby as localities for this species. It has been taken 

 by Mr. Norman and myself in many places in the counties of Northumberland and 

 Durham ; and I have also met with it frequently in the lakes of Selkirkshire, Dumfries- 

 shire, and Kirkcudbrightshire. Mr. Bobertson has taken it in the island of Cumbrae. 



The following remarks of Mr. King* relative to the habits of the Australian species, 

 " Newnhamia fenestrata,^^ are very interesting when considered in reference to those of 

 N. monaclius : — " This very common but interesting species lives almost wholly near 

 the surface of the water, its boat-like plate enabling it to walk along the under surface, 

 while its eyes, directed downwards, give immediate notice of the approach of an enemy. 

 When alarmed, it immediately sinks to a little distance, and then swims off, only coming 

 to the surface when all becomes tranquil. The hand passed over the water near the 

 surface, so as to intercept the light, or the surface being disturbed by the slightest 

 breath, instantly alarms them. They are the most active when the sun is shining ; and 

 often a whole troop of them may be noticed swimming round and round, and in and out, 

 with a most lively and graceful motion, about an inch beneath the surface, in some spots 

 more favoured than others by the warmth of the sun." 



Genus 5. Candona, Baird. 



Like Cypris, except that the lower antennae possess no tuft of setse, and that the 

 second pair of jaws are destitute of a branchial appendage. Setae of the upper antennae 

 short. Above the base of the postabdominal rami there is a short seta springing from 

 an enlarged base, somewhat similar to, but smaller than, that of Tontocypris (see Plate 

 XXXVII. fig. 2 i). The animals belonging to this genus have no swimming-power, and 

 are very sluggish in their movements, crawling leisurely on the bottom, or on the stems 

 of water-plants, or sometimes burying themselves in the mud. 



1. Candona albicans, Brady. (Plate XXV. figs. 20-25, and Plate XXXVI. fig. 12.) 



Candona albicans, Brady, Ann. & Mag. Nat. Hist. vol. xiii. (186i) p. 61, pi. iv. figs. 6-10, and Trans. 

 Tyneside Nat. Field Club, vol. vi. p. 107, pi. iii. figs. 6-10. 



Valves oblong, subreniform, nearly equal in height throughout, the left considerably 

 overlapping the right ; height equal to more than half the length. Anterior and pos- 



* Proc. Roy. Soc. Van Diemen's Land, vol. iii. part 1. 



