Dec. 13, 1877] 



NA TURE 



127 



of an inch apart, so that in order to be able to see the 

 double star ^ Ursas, which is a i" star, by means of an 

 eight-inch object-glass, all the surfaces, the 50 square 

 inches of surface, of both sides of the crown, and both 

 sides of the flint glass, must be so absolutely true and 

 accurate, that after the light is seized by the object-glass, 

 we must have those two stars absolutely perfectly distinct 

 at the distance of the seventeen hundredth part of an 

 inch, and in order to see stars ^'' apart, their images must 

 be distinct at one-half of this distance or at uj^y^th part 

 of an inch from each other. 



J. Norman Lockver 



( To be continued. ) 



BIOLOGICAL NOTES 



Classification of Decapod Crustaceans.— In 

 this well-defined group, the position of the anomurous 

 forms (hermit-crabs, &c.) has often been the subject of 

 doubt. The special adaptations of some genera for 

 particular modes of life have caused them to be thrown 

 together ; and no doubt they agree in possessing neither 

 the powerful abdomen of the lobsters, nor the very much 

 aborted one of the crabs. Yet the anomurous forms 

 include markedly contrasted groups. The family HippidcC, 

 with its lobster-like cephalothorax and firm abdomen, 

 differs greatly in aspect from the hermit-crabs. Hippa 

 talpoida, a small species found along the whole eastern 

 coast of the United States, inhabits sandy beaches 

 exposed to the waves, at a zone very near low-water mark. 

 It has a smooth oval form, and short and stout thoracic 

 legs (second, third, and fourth pairs), enabling it to 

 burrow backwards in the sand with marvellous rapidity. 

 In life the antennae are peculiarly crossed, with the 

 flagella curved round the mouth so that the setae, with which 

 they are densely covered, all project inwards, and the 

 function of the antennas appears to consist chiefly in the 

 removal of all parasitic growths or foreign bodies from 

 the anterior parts of the body. The appendages of the 

 mouth are not adapted for prehension or mastication, and 

 the alimentary canal is found loaded with fine sand. The 

 thoracic appendages have neither external nor superior 

 elements (exopodites, epipodites) ; while the ofifice of 

 protecting and cleaning the gills is discharged by the 

 small Umbs corresponding to the fifth pair of ambulatory 

 legs in lobsters, which are curved upwards and hidden 

 beneath the carapace. The development of this form has 

 been recently carefully described by Mr. Sidney Smith, 

 of Yale College, in the Transactions of the Connecticut 

 Academy, vol. iii. p. 311. They pass through larval 

 stages very analogous to the zoea stages of crabs, only 

 being destitute of a large dorsal spine j and they then 

 assume a form like the brachyuran megalops, with large 

 eyes, and powerful abdominal swimming legs. But in 

 this condition they buried themselves in sand with great 

 alacrity. Thus it is determined that the embryonic 

 development of Hippa, as well as of Albunea, studied 

 by Claus, agrees much more closely with that of crabs 

 proper than with hermit crabs or lobsters ; and this 

 publication by Mr. Smith furnishes an important addition 

 to the evidence favouring the view that the Anomura are 

 a heterogeneous group made up of specialised families of 

 Brachyura and Macrura. 



The American Bison.— Mr. J. A. Allen's valu- 

 able " History of the American Bison," so sump- 

 tuously produced by the Geological^, Survey of Kentucky 

 and the Harvard Museum of Zoology, has excited so 

 much interest that to supply the demand for it Dr. 

 Haydan has republished almost the whole of the text in 

 the ninth annual report of his survey of the territories, 

 and as a separate pamphlet of 150 pages, with con- 

 siderable additions by the author. One of the most 

 interesting of these consists in the publication of a letter 



from Mr. J. W. Cunningham, of Howard County, 

 Nebraska, on the domestication of this species. It 

 appears that the bison has been crossed with the ordi- 

 nary milch cow, and that half- and quarter-breds are 

 not uncommon, and the cows yield extremely rich milk. 

 They prove to be both hardy and tame. The colour of 

 the bison and the majority of the distinguishing characters 

 disappear after repeated crossings. The lump of flesh 

 covering the dorsal vertebrae also becomes diminished. 

 The preservation of a pure domestic breed of the bison 

 does not seem so easy. In some instances where buffa- 

 loes have been broken to the yoke they have proved 

 strong and serviceable, but rather unmanageable at times. 

 Unless the breed is maintained in some way artificially, 

 the wild species will no doubt before very long become 

 extinct. 



Products of Assimilation in Musace^.— Herr 

 Emil Godlewski has recently investigated whether in the 

 case of Musaceas the first assimilation-product is oil or 

 starch, which latter is the first product in most plants. 

 Sig. Briosi had recently maintained that oil was first pro- 

 duced. The question which had to be solved, therefore, 

 was whether these plants, when decomposing carbonic acid 

 under the influence of light, exhale a volume of oxygen 

 greater than that of the carbonic acid decomposed. If 

 oil is formed from the carbonic acid this must be the case. 

 Measurements which Herr Godlewski made to this end 

 with Musa sapientium, gave negative results ; the oxygen 

 exhaled was not of greater volume than the carbonic acid 

 decomposed. Sig. Briosi had failed to discover starch in 

 the grains of chlorophyll of the mesophyll-cells of the 

 leaves ; while Herr Godlewski was perfectly successful also 

 in this direction, perceiving numerous granules of starch in 

 leaves from young specimens of species of both Musa and 

 Strelitzia, which had been collected in the evening after a 

 hot day. 



Fertilisation in Thyme and Marjoram.— Under 

 the title of " Das Variiren der Gro;se gefarbten Bliithen- 

 hiillen, und seine Wirkung auf die Naturziichtung der 

 Blumen," Dr. Hermann Miiller reprints from Kosnios a 

 paper containing many of the facts which have appeared 

 from time to time with his signature in these columns. 

 The special point to which he calls attention is the 

 occurrence in many species of \.z!o\2X^— Thymus ser- 

 pyllum, Origanum vul^are, &c. — of two distinct forms, 

 one with larger hermaphrodite protandrous, the other 

 with smaller female flowers. The second of these two 

 forms can manifestly only be fertilised by the former, and 

 will disappear where the conditions of life are unfavour- 

 able ; while the propagation of the first form is in no way 

 dependent on the other. 



A Fossil Fungus.— One of the most interesting re- 

 cent discoveries in palaeophytology has recently been made 

 by Mr. Worthington Smith, in the detection, in the coal- 

 measures, of a fossil fungus nearly allied to that which 

 produces the potato blight, and which he has named 

 Peronosporites antiquarius. Fossil fungi were not pre- 

 viously altogether unknown. Some years ago Mr. Car- 

 ruthers, the keeper of the botanical department at the 

 British Museum, detected mycelial threads among the 

 cells of a fossil fern {Osmunda) from the Lower Eoceiie 

 strata of Heme Bay ; and Mr. Darwin has stated that 

 fungus threads in a fossil state in silicified wood were shown 

 to him more than forty years ago by the late Mr. Robert 

 Brown. Messrs. Hancock and Atthey have also described 

 in the Annals atid Magazine 0/ Natural History (4th ser. 

 vol. iv. 1869, p. 121, t. ix. X.), under the name of Archa- 

 garicon, what may be a fossil Peronosporites from the 

 Cramlington black shale. The specimen examined by 

 Mr. Worthington Smith (the fungoid nature of the 

 organism having been first suggested by Mr. Carruthers), 

 was seen within the vascular axis of a Lepidodendron, 



