56 



GL 0. SARS. 



[No. 1, 



developed young. On a closer examination, I found this was 

 uot the only specimen, my aquary containing several full-grown 

 specimens, all of which turned out to be females, more or les» 

 loaden with young brood in their incubatory cavity. Hence I 

 felt pretty sure of being enabled to prosecute my researches on 

 this most interesting form. The difficulty first encountered in 

 proving the presence of the specimens in my aquary, I found to 

 be due to their peculiar habits. For they are far less active 

 animals than most other Phyllopoda, often resting, as they do, 

 apparently for a considerable time, quite immobile in the same 

 place, either immerged in the loose mud of the bottom or con- 

 cealed within some cluster of Confervæ. Only at intervals do 

 they make a short trip through the water, very soon, however, 

 sinking back to the bottom or clinging, by the aid, it would 

 seem, of the recurved spines of the antennæ, to some submerged 

 object. During this apparent immobility, however, the legs are 

 found on closer examination moving rapidly in the above-described 

 peculiar rhythmical manner, partly for the purpose of performing 

 the necessary aération of the blood, partly for that of conveying 

 food to the mouth. Meanwhile the oral parts exhibit an almost 

 continual activity, the labrum being at intervals lowered and 

 then appressed against the mandibles, the latter organs perform- 

 ing their characteristic adductory and rotatory movements. Only 

 when the animal is suddenly disturbed, are these movements inter- 

 rupted for a short time, the head and tail being rapidly with- 

 drawn into the shell, and the valves closed by the aid of the 

 adductor muscle. But very soon the valves again open, the 

 anterior part of the head, together with the antennæ, being 

 slowly and, as it were, cautiously exserted from the front part 

 of the shell, in which case the recurved spines of the antennæ- 

 are the first to appear, projecting bey ond the edges of the valves; 

 then the caudal plate is thrown out from the inferior edges, 

 whereupon the legs and oral parts immediately recommence their 

 peculiar movements. 



Maybe the animals are more active in their natural habitat, 

 and the much lower temperature in our country tends to abate 



