Miscellaneous. 231 



from naturalists ; and the very incomplete investigation of it made in 

 18G0 by M. Keferstein taught us nothing of importance about it. 



The Balanoglossi nevertheless constitute one of the most curious 

 of animal types, the position of which in the zoological scale is not 

 easy to fix. This appears evidently from the fine work of M. 

 Kowalewsky. 



The body in the Balanoglossi (of which two species exist at 

 Naples) is vermiform and composed of a series of successive regions. 

 The foremost, separated by a constriction from the following one, 

 has all the appearance of a head ; but a careful examination shows 

 that it possesses none of the characters which would justify that 

 name. It is no doubt a tactile organ, to which M. Kowalewsky gives 

 the name of trunk. It is followed by a sort of muscular collar 

 bearing the mouth vmderneath. The succeeding region is much 

 longer, and may be designated the branchial region. We shall recur 

 immediately to its singular structure. Further back the body bears 

 upon its back two rows of glands (the sexual glands), and then nu- 

 merous papilloe, which Delle Chiaje took for respiratory organs, but 

 which in reality contaiu blind processes of the intestinal canal : 

 this, therefore, might be called the hepatic region. Lastly, the 

 terminal or caudal region is smooth and finely annulated. 



The most remarkable peculiarity of the Balanoglossi is the struc- 

 ture of the respiratory appai'atus. The water which serves for the 

 oxygenation of the blood penetrates by the mouth and issues upon the 

 back of the animal by two series of apertures placed upon the sides 

 of the branchial region. It traverses a very complex branchial 

 apparatus, sustained by a chitinovis skeleton. This skeleton is 

 formed by two symmetrical series of vertical transverse plates, 

 united in threes by small rods perpendicular to the direction of the 

 plates. The whole therefore constitutes a double series of frames, 

 upon which ramify the blood-vessels, covered by an epithelial layer. 

 The openings of the frames are covered with vibratile cilia. The 

 water, after penetrating by the mouth into the pharynx, gets en- 

 tangled in the respiratory frames, and issues by the orifices which we 

 have mentioned, the number of which is equal to that of the frames. 



It is impossible, in our opinion, not to be struck by the great 

 resemblance of this apparatus to the branchial apparatus of the 

 Vertebrata. Certain anatomists have already attempted a compari- 

 son of the Ascidia with the Vertebrata, in consequence of their sin- 

 gular respiratory apparatus ; but in this case the resemblance is very 

 much greater. 



No doubt, in other respects, the analogy with the Vermes is 

 striking, especially as regards the facies of the animal and the cen- 

 tral portions of the vascular system reduced to two principal trunks 

 — a dorsal vessel driving the blood from behind forwards, and a 

 ventral vessel conveying it in an opposite direction, &c. Neverthe- 

 less it appears to be impossible to ascribe to these animals, as M. 

 Keferstein has done, a place among the Nemertida, or especially to 

 approximate them to the Annelida, as M. Kowalewsky would do. 

 For the present it is necessary to elevate the Balanoglossi into a 



