303 



DENDRODUS. 



DENTALIUJI. 



3C6 



the base on one side a forked branch, on the other a simple one, all of 

 the same thickness. Mr. M'Leay remarks that the organs of digestion 

 have great affinity in external structure and position to those of 

 Cynthia pantex of Savigny, except that the stomach and intestine are 

 horizontal, and the anus simply margined, and that, different as this 

 species is in external appearance from all other Ascidice, internally it 

 agrees with the Pandocice in almost every essential respect but the 

 ovary. He observes that this singular animal completes the circle of 

 the genus Ascidia in the most beautiful manner. It agrees with the 

 first sub-genus, Cynthia, in the nature of its branchial reticulation and 

 of its digestive apparatus ; but Cynthia has two ovaries, the right one 

 contained in the intestinal loop, and the left one coating the tunic. 

 The first of these, or the right ovary, is the only one possessed by Pan- 

 docia, and the left is the only one possessed by Dendrodoa. Mr. M'Leay 

 concludes by stating that the distinction between the aberrant groups 

 of Ascidia depends thus upon the nature of their system of gene- 

 ration, aa that which exists between the two normal groups depends 

 on their system of respiration. 



(Anatomical Observations on the Natural Group of Tunicata, &c., 

 by \V. S. M'Leay, ; Linn. Tram., vol. xiv.) 



DE'NDRODUS, a genus of Placoid Fishes, from the Old Red- 

 Sandstone of Elgin, Moray, and Russia. Professor Owen has described 

 five species, and Agassiz a sixth. 



DE'NDROMUS, a genus of Animals belonging to the order 

 Jtodentia, established by Dr. A. Smith in his ' Contributions to the 

 Natural History of South Africa,' with the following characters : 



Incisors,!; Molars, ?=? = 16. 

 2 3 3 



The upper incisors with a longitudinal furrow on their anterior 

 face ; the lower long, slender, with the cutting edge cuneated. 



The upper first molar with six tubercles in a double row, and two 

 indistinct ones besides, of which one is at the anterior part of the 

 crown of the tooth, the other near another tubercle of the internal 

 series, behind the tarnsverse incisorial lamina ; the second molar 

 with two or three longitudinal incisorial lamina; by the external 

 margin of the crown, in the middle of which lie three or four obtuse 

 transverse tubercles disposed in a row ; the third molar has two trans- 

 verse incisorial laminae with an interjacent furrow. Below, the first 

 molar has six tubercles disposed in a double series ; the second, four 

 obtuse tubercles arranged in the same order ; the third is very small, 

 with some transverse lamina; and furrows intermingled. No canines. 

 Rostrum acute. Lip slit. Ears oblong, rather naked, and internally, 

 near the skull, with two transverse membranaceous valvules, of which 

 the lower lies over the external auditory meatua Tail elongated, 

 annulated, with scattered hairs. Feet divided, ambulatory; the 

 anterior with three toes, and a wart in lieu of hallux ; the posterior 

 five-toed : claws falcular. 



D. Tyjiui. Above, brown, passing to ferrugineous ; beneath, 

 reddish-white ; whiskers long, partly black and partly white ; upper 

 lip white; ears without and within slightly covered with a fine 

 abort reddish-white fur ; extremities the same ; tail pointed, consider- 

 ably longer than the body, and of a faint grayish-brown colour ; 

 along the centre of the back, particularly towards the tail, an 

 indistinct black line. Length from point of nose to root of tail, 34 

 inches: length of tail, I 1 , inches. 



It inhabits South Africa, where it is found upon the branches of 

 trees, &c., in which situations it constructs its nest and brings forth 

 its young. Dr. Smith observes that the position of this little 

 animal among the family of mice is not well determined ; but that 

 ]:rhaps its place is after the Mouse. ('Zool. Journ..' vol iv. p. 438.) 



HKVDROMUS. [DUCKS.] 



DENDRONESSA. [DUCKS.] 



DE'NDROPHIS (Fitzinger), a genus of Serpents placed by Cuvier 

 under the great genus Coluber, and stated by him to be the . I luttulla 

 of Gray. The species of this genus have, like the Dipiai of Laureuti, 

 a line of wider scales along the back, and narrower scales along the 

 flanks, but their head is not larger than their body, which is very 

 slender and elongated. Their muzzle is not elongated, and they are 

 not venomous. They inhabit India and Africa. 



DENDROPHYLLIA. [MADREPHYLLKEA.] 



DE'NDROPLEX, a genus of Birds established by Mr. Swainson, 

 and placed by him in the family Certhiadce (Creepers), and sub-family 

 Vfrthiana, which have the tail graduated and rigid. 



The bill is very straight. Wings moderate, rounded ; third, fourth, 

 and fifth quills longest. 



Mr. Swainson observes that he knows not whether the type of this 

 genus hag been described, and states that the living bird has all the 

 manner of a Pieui. Except in ita perfectly straight bill, he adds, it 

 differs not from Dendrocolaptet. (' Zool. Jouru.,' vol. iii. p. 354.) 



DENTA'LIUM, a genus of Gasteropodous Afollusca, whose place 

 in the animal series was first satisfactorily determined by M. Deshayes. 

 Hondelet considered the Denlalia marine shell-worms (vermis- 

 neaux de mer), though he noticed them as worthy of particular atten- 

 tion. Lister introduced them at the end of the Limpets (Patellce). 

 Lang followed in marly the same steps, separating, after the Pattlltp, 

 a section wherein he arranged, together with the Dentalia, all the 

 calcareous tubes of Annelides then known. Breyne placed his genus 

 Tubului, containing the Dentalia, lie., at the head of his Monotha- 



*AT. nisi. DIV. VOL. ii. 



1, Dendropha Ahirtulla, one fourth of the natural size j 1 a, head ; 1 6, dispo- 

 sition of the scales above and below the cnt. (Iconog.) 



lamous Shells, the first of the two grand orders, the Monothalamous 

 and the Polythalamous, into which he divided the Testaceans. In 

 this position Dentalium was separated from the Patella; by all the 

 other univalve shells comprised in the CoMidia, as well as by the 

 Polythalamous series ; in short, by the entire interval of the Univalve 

 Testaceans ; Breyne, as M. Deshayes observes, having probably con- 

 sidered the Patellae as the passage from the univalves to the bivalves, 

 for he places them immediately before the latter. Tournefort gave 

 the Patellae a position at the head of the univalve shells, and at the 

 end, before the bivalves, he placed the Dentalia, Entalia, and the 

 other marine testaceous tubes. D'Argenville, in his ' Zoomorphose,' 

 appears to be the first who attempted to give any notion at all 

 approaching to reality of the animal, the result of a note and drawing 

 which had been sent to him from India. Though the materials were 

 too incomplete to furnish secure data for fixing its position, they gave 

 information which former authors had not enjoyed, and there was 

 certainly enough to prevent D'Argenville from placing it in the 

 heterogeneous third division of his system, denominated by him the 

 Multivalves. Linnaeus arranged it immediately after Patella, and 

 before Serpula, stating the animal to be a Terebella, and the shell to 

 be univalve, tubular, straight (recta), mouothalamous, and pervious 'at 

 each extremity. Bruguicre gave it nearly the same position : but if 

 both these zoologists were right iii making Dentalium, follow Patella, 

 they were as fur wrong in placing it by the side of Serpula, Teredo, 

 Sabella, and above all, Af]iergillum. Lamarck, in his 'Systeme dus 

 Animaux sans Vertebres' (1801), arranged Dentalium with Terebella, 



x 



