July 1, 1SGG.] 



SCIENCE-GOSSIP. 



147 



cost and trouble from England, and not procurable 

 save by rare chance any nearer here) from the ag- 

 gressions of their fellow prisoners; and this is a 

 constant source of difficulty for me, for large as this 

 establishment is, and many as are the separate 

 tanks, they are not numerous enough to contain all 

 the kinds of creatures which can be got, without 

 most of them meeting with enemies of some sort — 

 active or passive — in the same receptacles ; and yet 

 all the animals, whether friendly or unfriendly to each 

 other, arc of interest to the public. For example, 

 sometimes when food is given to the mullets, and 

 long before they are aware of its presence on the floor 

 of the tank, an enormous black goby will rush out 

 of its hidiug-place, and, while its colours are rapidly 

 changing from inky blackness to pale grey, and vice 

 versa, according to the wont of many fishes when 

 excited, it will seize hold of the food, and if too 

 large to be carried away bodily, will shake it like a 

 terrier dog, and hover about it for a long time, so that 

 the mullets get no chance ; and indeed they would 

 have but a sorry life if it were not that the 

 black gobies are bottom fish and the mullet are not. 

 Then, at nightfall, the rocklings, which hide nearly 

 all day, issue forth, and are quite as tyrannical 

 as the gobies. Therefore the only plan I can adopt 

 is first to feed these antagonistic fishes to satiety at 

 proper times, such as late at night, on mussels and 

 other kinds of food which the mullets do not much 

 care for. The blenuies tease the mullets but do not 

 harm them much, as the former are small specimens, 

 and they themselves have been much thinned down of 

 late by their fellow ground-fish the black gobies. 

 And so the war goes on : whatever changes of ar- 

 rangement are made, some enemy is sure to be 

 found. There is another difficulty, that of having 

 to keep animals which will not eat anything. The 

 pogge or armed bullhead {Aspidophorus cataphractus) 

 is an example of this perversity. Eishermen tell 

 me that they see them when in the sea, or in their 

 well-boats, feeding freely on shrimps, and these 

 crustaceans can be found in their stomachs ; but in 

 an aquarium, neither shrimps nor any other food I 

 have ever offered them will induce them to eat. All 

 day they repose motionless at the bottom of the 

 tank, and at night they occasionally take a laborious 

 swim and settle down again, and this is all I have 

 ever seen them do till they die. Of very different 

 habits is their first cousin, the father-lasher, or sea- 

 scorpion {Coitus scorpius). It, indeed, can be kept for 

 any time, as it has an insatiable appetite in confine- 

 ment, and will swallow anything and everything, 

 alive or dead, which will pass into its huge cavernous 

 mouth. It is an expensive fish to keep, for not only 

 does it devour most other animals weaker than itself, 

 but it demands a large tank in order to thrive well. 

 But it is an attractive and curious-looking fish, and 

 deservedly a favourite with visitors. 

 Hamburg, W. Alford Lloyd, 



P.S.— Feb. 1st. The mullet still continue to im- 

 prove and grow, and all have nearly recovered their 

 lost tails. Their appetites, too, have got to be more 

 universal, and they will freely eat the flesh of the 

 oyster or mussel. But they will leave anything for 

 Crustacea flesh. — W. A. L. 



Note.— April 20th. The mullet have grown 

 much lately, and they take a greater variety of food 

 than at first. Only one has died here. I have at 

 length got Aspidophorus to feed on living Mysis 

 ekamtekon, a small shrimp -like crustacean of rather 

 less than an inch long, found abundantly in the 

 Baltic Sea at Kiel, and besides being thus useful 

 for breeding purposes, it is itself an interesting 

 aquarium object. Unlike the shrimp, which usually 

 burrows out of sight in the sand, taking now and 

 then a flight in the water above, and also unlike 

 the prawn, which passes much of its time in 

 clinging, partially hidden, to rocks, Mysis is ever 

 perpendicularly suspended in mid-water, and when 

 some hundreds are present in some tanks, and 

 thousands in others, the effect produced by their 

 being thus all quite parallel to each other is a very 

 singular one.— W. A. L. 



II 



DESMIDIACE^l. 



AVING dealt with the most common genera of 

 desmids, we proceed to notice a few others 

 which, though not so plentiful as those enumerated, 

 are yet too frequently met with to be excluded from 

 our chapter. 



We have made great efforts to obtain the speci- 

 mens necessary for the purpose, in the neighbour- 

 hoods of Keston (Kent), Esher, Wimbledon Com- 

 mon, and Streatham. The bog at Keston yielded 

 our most beautiful examples, and our richest collec- 

 tion. The other localities produced more limited 

 supplies, and, with some exceptions, the specimens 

 were not so bright in colour. 



After allowing each gathering to settle, the super- 

 fluous clear water was poured off, and the residue 

 of mud, &c, was placed in the light, to enable the 

 desmicls to extricate themselves under its potent in- 

 fluence. This they did very readily, congregating 

 in tiny green clusters on the top of the sediment. 

 Any one of these clusters, removed to a glass slide 

 and examined, presented a most beautiful appear- 

 ance. 



Closteria appear to be more generally distribu'ed 

 than any other Desmidiacete. We found many kinds 

 in all our gatherings : occasionally, self -division was 

 seen, and one or two examples of conjugation oc- 

 curred with a species ha,ving attenuated ends (pro- 

 bably C. setaceum or C. rostratum), which we 

 gathered at Streatham (Telford Park). 



The genera Penium and Docidium bear a close 

 resemblance to Closferium, both in outward form 



