June S, 1883.] 



SCIENCE, 



513 



ing to the organization committee of each session 

 the care of detailing its programme, desires that in 

 future a place should be reserved foi- purely scientific 

 studies, besides the works of unification; and also 

 wishes, that, following the example given at Bologna, 

 an exhibition of collections and maps should accom- 

 pany each session of the congress. J. B. Marcou. 



DEVELOPMENT OF THE MEMBRANE- 

 BONES OF THE SKULL OF THE 

 PIKE. 



I'S an inaugural dissertation presented to the 

 faculty of the university of .Jena, which has been 

 published separately, and also in the Jenaische zeit- 

 schrift {xvl. 59-87, 1882), ^ with two excellent plates, 

 Johannes Walther disCHSses this subject very ably, 

 and reaches the following conclusions, which are 

 probably of considerable importance as leading to 

 important general views respecting the development 

 of the membrane-bones of the skulls of Teleostei. 



The skull of the pike (Esox lucius) consists of 

 membrane and cartilage bones. The former develop 

 in the following ways : 1. As cementum-bones, by the 

 coalescence of osseous cementum-plates developed 

 below the bases of the teeth, which are formed in 

 invaginations of the oral mucous membrane; 2. As 

 membrane-bones in the subcutaneous connective 

 tissue, independently of any antecedent development 

 of teeth; .3. As perichondrial bones, like the last, but 

 in a deeper layer in contact with the perichondrium. 

 These three modes of development of the parts of 

 the osseous skull are connected together by transi- 

 tional modes. According to a fundamental biological 

 law, as well as in view of the evidence afforded by the 

 studies of O. Hertwig in the comparative embryology 

 and anatomy of the scales, dermal scutes, etc., of 

 fishes, the preceding types of osteogenesis constitute 

 a series of stages which correspond to the phylo- 

 genetic mode of evolution of the bones in question. 



The cartilage-bones of the pike's skull develop 

 outwards from the perichondrium, though there is a 

 centripetal growth of osseous tissue during which 

 the cartilage is absorbed. The origin of bone-corpus- 

 cles Inside of cartilage, or enchondrally, was not 

 observed in any of the stages investigated. The 

 vomer, palatine, and dentary bones are conspicuous 

 instances of the first-mentioned mode of ectosteal 

 development from the fusion of basal, osseous, tooth- 

 supporting plates, which the author regards as repre- 

 senting the cementum. The maxillary, jugal, frontal, 

 nasal, parietal, and parasphenold bones, although 

 not ontogenetically developed in tills way, are true 

 membrane-bones, and are derivable primarily or phy- 

 logenetically from coalesced basal dentary plates. 



The author finds an enamel cap surmounting the 

 conical hollow dentinal bodies of the teeth which 

 contain the pulp. The conical dentinal cap is the 

 first part of the tooth to be formed ; the enamelled 

 tip is then developed previous to the anchylosis of 

 the whole to the osseous basal plate, the dentine 

 growing downwards to meet the latter. 



The paper also contains observations on the de- 

 velopment of the teeth of the young trout, California 

 salmon, common salmon of Germany, and the eel. 

 The morphology of the skull of Esox is very fully 

 and admirably treated, the histological details and 

 crania of the larval stages figured and described 

 constituting a real addition to our knowledge. 



J. A. Kydbb. 

 1 See also Science, IT 738. 



LETTERS TO THE EDITOR. 

 Rainbo-w. 



Last evening I observed what to me was a new phe- 

 nomenon. The day had been clear. Towards sunset 

 the sky clouded in the west with rain-clouds, so that 

 the sun appeared through them only as a white spot 

 of light. The clouds were continuous, but uniformly 

 lighter from the horizon upwards. At quarter of 

 seven o'clock a rainbow, faint, but still distinct in 

 form and color, was visible above and to the northern 

 side of the sun. It extended, perhaps, something less 

 than two-thirds of the way from the horizon in the 

 north to that in the south. The phenomenon is of 

 course easily understood, but is it common? 



W. J. L. 



Andover, N.H., May 15, 1883. 



Nemestrinidae. 



In the notice of Handlirsch's discoveries as to 

 the life-history of Hirmoneura obscura (Science, 

 p. 332), I stated (following Osten Sacken's catalogue) 

 that Hirmoneura was the only genus of Nemestri- 

 nidae in the United States. Dr. Willislon kindly 

 reminds me that I overlooked his description of 

 Rhynchocephalus Sackeni from Washington Terri- 

 tory, published in 1880 {Trans. Conn, acad., iv. 243). 

 He now publishes {Canadian ent., April, 1883) a 

 paper on the North-American species of that family, 

 in which he describes from my collection a third spe- 

 cies ; viz., Rhynchocephalus volaticus from Florida. 

 While speaking of this dipterous family, I would also 

 mention that Baron Osten Sacken ( Wiener ent. zeit., 

 ii. 114) calls attention to a short communication by 

 E. L. Arrlbalzaga, published in El naturalista Ar- 

 gentina, i. 275 (1878), on the life-history of Hirmo- 

 neura exotica Wied. , which oviposits in the galleries of 

 a carpenter-bee (Xylocopa augustii St. Farg. ). This 

 last constructs its cells in fence-posts and in the 

 wood-work of buildings. Nothing further is stated 

 by Arribalzaga ; but the young larvae doubtless 

 leave the burrows, and otherwise resemble those of 

 H. obscura. C. V. Riley. 



Intelligence of the orovsr. 



In Science, Nos. 13 and 16, are letters bearing 

 this title, in the former of which the writer refers to 

 crows assaulting him while walking in Rome by at- 

 tempting to drop stones upon him as they circled 

 above. The author of the second letter takes ex- 

 ceptions to the statement, especially to that part 

 of It averring that the crows dropped the stones 

 from their claws, and thinks the narrator must have 

 been ' mistaken in the bird,' basing his belief on 

 his own experience with crows and ravens in con- 

 finement, which he has observed always to use their 

 bills In transporting objects. Whatever the crows 

 may ' do in Rome,' it is well attested that rooks 

 (Corvus frugilegus), which are true crows, have been 

 seen to carry mussels from the beach to a consider- 

 able distance into the air, and let them fall among 

 stones to break the shells, so as to get at the contents. 

 Gulls are well known to occasionally resort to the 

 same practice. Although in neither case do the ac- 

 counts I have seen state explicitly how the mussels 

 are carried, the inference is that they are taken in 

 the bill. Yet as woodcocks have been seen to trans- 

 port their yotmg by flying with them supported be- 

 tween the feet, it is obviously unsafe to dogmatize as 

 to what a given species of bird ma:y or may not be 

 able to do. J. A. Ali-en. 



