HARDWICKE'S SCIENCE-GOSSIP. 



of the (leld of view, absence of spherical and chro- 

 matic aberrations, convenient distance of the ob- 

 server's eye from the object observed, ten times the 

 amplification practically attainable with the single 

 microscope, and, lastly, the very great advantage 

 of true stereoscopic vision. With the instrument 

 described any portion of the integument, from the 

 scalp to the soJes of the feet can be conveniently 

 examined, and a prolonged examination can be made 

 without fatigue to the observer. The ordinary 

 diffused light of a bright day affords ample illus- 

 tration with all the objectives except the half-inch. 

 Eor this'we need direct sunlight. If the examina- 

 tion be made at night, or in a dark place, the light 

 from a Tobboed, or other good illuminator, concen- 

 trated upon the object, with a mirror or bull's-eye 

 condenser, will answer every purpose." 



ZOOLOGY. 



Tiie "Congo Snake."— This curious animal, 

 which is reported in Science-Gossip, July I, p. ]G1, 

 a-s a novel addition to the Manchester Aquarium, 

 and called the Congo Snake, or Muranopsis tri- 

 (lactijla, is perhaps the same as the Amphiuma 

 tridactylum, which has long lived and grown rapidly 

 in the reptile-house of the Zoological Society's 

 gardens at the Regent's Park, London. Another 

 species, with only two fingers, was described by 

 Cuvier, but later zoologists have considered this as 

 only a variety. Amphiuma belongs to those Sauro- 

 batrachians which have temporary gills, while its 

 allies, the Siren, Proteus, and Axolott, have per- 

 manent gills. This fact is important, because in our 

 books of comparative anatomy the largeness of the 

 red blood-corpuscles is said to be correlated to the 

 persistency of the gills, an error which was em- 

 braced, after Rudolph Wagner, by Professor Owen. 

 But the truth is that Amphiuma has evanescent 

 gills and the largest blood-corpuscles yet known ; 

 while in another caducibranchiate species, Sieboldla, 

 these corpuscles are larger than those of the perermi- 

 branchiate Sirenian or Axolott. When an oppor- 

 tunity occurs, preparations should and could easily 

 be made of the red blood-corpuscles of Amphiuma. 

 These would form a very novel and acceptable 

 addition to the microscopic cabinet. They are so 

 large as to be visible to the naked eye, being con- 

 siderably larger than the magnificent blood-discs of 

 the Proteus, Siren, and Sieboldia. And it is note- 

 worthy that the blood-corpuscles of Lepidosiren in 

 their largeness present this remarkable sauro-ba- 

 trachian character, which has never yet been found 

 in the class of true fishes, with which this para- 

 doxical creature is often associated by zoologists, 

 although the late D. J. E. Gray and other eminent 

 authorities consider it rather as a batrachian than a 



fish. Some of the family of (Proteids, to which 

 all the Saurobatrachians belong, have often been 

 regarded as larvae of unknown Salamanders, but 

 this notion is no longer entertained. Amphiuma was 

 known upwards of a century ago to that excellent 

 naturalist, Dr. Garden, of Charlestown, who men- 

 tioned it particularly in his correspondence with 

 Ellis ; and, after the lapse of more than fifty years, 

 Harlan, the North Ameiican naturalist, and the 

 illustrious Cuvier, made the Amphiuma more gene- 

 rally known. It is peculiar to North America, 

 while its ally, the Proteus, is a native of Europe. 

 Seeing how well the Amphiuma has thriven in 

 London, we may hope yet to see both sexes intro- 

 duced to England and breeding in confinement, so 

 as to afford us an opportunity of witnessing how 

 long the creature retains its gills, and other inter- 

 esting points in its habits and economy. The size 

 and development of the blood-corpuscles in the 

 young animal would be well deserving of investi- 

 gation. Those cf the adult were compared, by 

 Professor Gulliver, in the drawings illustrating his 

 communication to the Zoological Society, June 15, 

 1875, with the corresponding corpuscles throughout 

 the vertebrate sub-kingdom, and their dimensions 

 given in very extensive tables of measurements. 



Cassowaries.— It was stated in the article on 

 " Wingless Birds " that only two species of Casso- 

 waries are known. Dr. Sclater, in a paper read 

 before the Zoological Society in January last, gives 

 a list of nine. These are Casuarius galeatus, from 

 Ceram ; C. Beccarii, from Wokau and the Aroo 

 Islands ; C. australis, Northern Australia ; C. hica- 

 runculatus, from the Aroo Islands ; C. uniuppendicu- 

 latus, Papua; C. papuanus, Northern Papua; C. 

 IFestermanni, from the island of Jobie; C. pied- 

 collis, Southern Papua ; and C. Bemetti, from New 

 Britain. 



Profusion of "Brown-tail" Caterpillars. 

 — I have already noted that in several hedges near 

 Gravesend the caterpillars of the above moth 

 (Liparis chrysorrheca) were abundant in 1871. No 

 measures were taken for their extirpation ; indeed, 

 though writers in natural history tell us the species 

 was at one time dreaded by horticulturists, it is not 

 at present an object of fear, most probably because 

 of its comparative rarity. Despite the cold spring, 

 in the locality named the caterpillars are still more 

 common this season, positively defoliating a mixed 

 hedge of hawthorn, sloe, and blackthorn, shunning 

 cautiously an occasional maple. It is important to 

 know, could one ascertain, whether the caterpillars 

 of the " Brovrn-tail " have really the propensity for 

 attacking fruit-trees ascribed to them by some 

 authors. As far as I have observed, they are little 

 inclined to migrate, and gnaw the wood of the 

 hawthorn rather than undertake a foraging journey 

 across a road. It would be easy to collect and 



