254 



NATURE 



[July 13, 1882 



deductions, in spite of his mistake about the temporary 

 continuity of the mandibular and hyoid arches, appears 

 to me to be absolutely incontrovertible. 



As far as I have seen, there is no other type in which 

 the hyoid "cornu" is chondrified continuously with Meckel's 

 cartilage, or the endoskeletal lower jaw. 



This may be an acquired peculiarity, but I rather in- 

 cline to the view that it is an old hereditary characteristic, 



(5V 



% — 



Fie. 5 



x JO 



: stage, more advanced, 5 inches long), 

 e ; the internal face of the stapes, st. is 



Fig. 5. — Same species as last (s; 

 outer view. Lettering the i 

 shown. 



derived from a very remote ancestry, in which the visceral 

 arches formed a basketwork of cartilage, and not a 

 series of properly segmented arches, such as we are 

 familiar with in most fishes. In somcfislies, the " marsi- 

 pobranchii " — Hag and Lamprey — we still see this lower, 

 non-differentiated state of things. 



There is a small distal part to the lingual or hyoid 

 arch, but the lower part of the "cornu" (cerato-hyal) is 



m.sf 



Fie. 6 



Fig. 6. — Same species as last (seventh stage, ripe embryo, 10 inches long), 

 outer view. Lettering the same, with addition of ?, quadrate bone ; 

 vii., facial nerve. 



aborted by the continuity of its upper half with the lower 

 jaw. 



The rest of the arch resembles the branchial arch of a 

 fish, and is like the proper hyoid arch of a Chimsera ; the 

 segments correspond very closely, but there is one piece 

 too many, but this intercalary piece — the " inter-hyal " — 

 is found in ganoid and osseous fishes — uniting their 

 hyomandibular with their epihyal. 



This fish-like hyoid soon becomes a continuous bar, as 

 in the New Zealand Lizard {Hatteria), where the auditory' 

 columella and the hyoid arch are one continuous struc- 

 ture. 



That condition, however, in the Crocodile, is only 

 continued through the middle part of the term of incuba- 

 tion ; towards the latter part of the time the parts that 

 were fused all come to pieces again, and the ripe young 

 has a free columella, with small, distinct nuclei of carti- 

 lage attached to the hinder margin of the ear-drum, these 

 are remnants of the epi-, inter-, and cerato-hyals — the 

 latter become free from the lower jaw during the middle 

 of the incubating period. 



The complex triple Eustachian tubes are formed after 

 the middle of incubation, but before that time the basis 

 cranii had become hollowed out, and so also had the 

 quadrate and the articular end of the mandible. 



By the time of hatching there are in the complex 

 tympanic labyrinth or diverticula of the ist visceral cleft, 

 the following parts, namely : — 



a. The drum-cavity hollowed out of the quadratum. 



b. The middle, single, and the lateral, forked Eustachian 

 tubes. 



c. The extension of the tympanic cavity into the whole 

 posterior sphenoid, base and wings, into the periotic bones, 

 and into the whole circle of the occipital arch or ring. 



d. Through the " siphonium," into the articular region 

 of the lower jaw. 



The investing bones are solid ; only the ossifications 

 of the primary chondrocranium are pneumatic ; this 

 hollowing out begins to take place before ossification 

 sets in. 



The pneumaticity of the Crocodile's endocranium is 

 similar to what obtains in birds, the whole tympanic 

 labyrinth in the two types is singularly like, and singularly 

 unlike. 



N ote. — For descriptions of these parts in the bird-class I 

 must refer the reader to my papers in the Royal, Linnean, 

 and Zoological Societies. A full account of the develop- 

 ment of the skull of the Crocodilia will soon appear in 

 the Transactions of the latter society. 



W. K. Parker 



PROF. HAECKEL IN CEYLON AND INDIA 

 I. 



PROF. ERNST HAECKEL of Jena, as most of the 

 readers of Nature are doubtless aware, has lately 

 returned to his University after a six months' journey in 

 India and Ceylon, undertaken in the interests of science 

 with the object of providing additional data in support of 

 the theory of evolution, of which he is the most able and 

 best-known exponent in Germany. The veneration which 

 he constantly expresses for Mr. Darwin, of whom he may 

 be said to have been the first and perhaps the chief 

 disciple on the Continent, would of itself suffice to give 

 his opinions and observations weight in this country. No 

 one, however, who has read the series of letters now being 

 contributed by Prof. Haeckel to the Deutsche Rundschau, 

 can fail to find them on their own merits both delightful 

 and instructive. They are written in a popular form, but 

 contain traces of profound scientific knowledge combined 

 with great quickness and freshness of observation, and an 

 almost bo\ish exuberance of delight in the presence of 

 nature's wonders. Of the three letters or articles already 

 published, the first contains an account of the voyage to 

 India, the second, entitled "A Week in Bombay," 

 describes with vivid enthusiasm the caves of Elephanta 

 and the other marvels of that most interesting of tropical 

 cities, and the third, contained in the June number of the 

 Rundschau, of which we propose to give a short repro- 

 duction for the benefit of our English readers, brings the 

 Professor to the " promised land" of his scientific yearn- 

 ings—that island of Ceylon which exhibits in all its varied 



