ORCELLA. 383 



I shall have occasion afterwards to show in Plafanisia gangetica. In Orcella, the 

 duodenal folds (PI. XXVII, fig. 10), instead of forming regular lappets running 

 quite across or around the cavity, have short rugse dhected partly longitudinally, 

 partly obliquely, and partly transversely ; and these enclose more or less lozenge- 

 shaped depressions. In this respect Orcella does also not agree with the allied 

 genus Olobicephalus as described by Dr. Murie. 



Narial chamber and appurtenances. — In the description of the exterior of the 

 animal, mention has been made of the crescentic blow-hole. The posterior nares, 

 it may be observed, present much the same characters as in Flatanista, afterwards 

 to be fully treated, save that the large arched crypts that occur in the latter genus 

 are exceedingly small and irregularly distributed in Orcella. 



The spiracular sacs of several genera of the Delpldnidce have been described 

 and figured, and their homology discussed by various writers, more particularly by 

 John Hunter^ and Von Baer" and Sibson,'' and more recently by Murie.* The account 

 and illustrations given of the sacs of GlobicepjJialus melas by the last mentioned 

 author are borne out in most respects by my examination of those of Orcella brevi- 

 rostris. On each side of the blow-hole and within is a more or less irregular 

 flask-shaped thinnish-walled bag, the so-called " maxillary sac :" behind these are 

 tortuous narrow canals, as thick as a goose-quill, whose openings are into the com- 

 mon spiracular cavity, the so-termed "naso-facial" sacs or passages. Quite at the 

 bottom of the blow-hole cavity, and resting on the front of the skull, are the 

 large "premaxillary" bags, directed forwards and overlaid by the mass of fibrous 

 tissue and blubber. The resemblances and differences between these accessory 

 nasal organs and those of the Gangetic Dolphin (Flatanista) shall be treated of 

 further on. 



Pharynx. — Beyond the presence of a wide glandular orifice situated near the 

 base of the tube of the larynx and its longitudinal folds, the pharynx does not call 

 for any special description. The gland is racemose and of the same nature as the 

 glands investing the faucial region, and which are apparently identical with the 

 secreting crypts opening by pores on the pharynx of Balcenoptera rostrata described 

 by Carte and Macalister,* and from which was expelled a quantity of viscid mucus. 

 Similar glands have also been described by Turner*' in the pharynx of BalcBnoptera 

 sibbaldii and by Murie'^ on the fauces of Globicephalus melas. It is situated internal 

 to the articulation of the arytenoids with the cricoid cartilage, and its position in 

 this locality, on the supposition that it is a mucous gland, would seem to radicate 

 that its special function was to lubricate this portion of the mucous membrane and 

 so facilitate the movements of the two cartilages of the larynx on each other in the 

 respiratory act. 



1 "Observations on the structure and economy of Whales;" Phil. Trans. 1787, vol. xvi. p. 335. 



2 "Der nase der Cetaceen," Isis, 1826, p. 811. 



3 Phil. Trans. 1848, p. 117. 



■• Trans. Zool. Soc. vol. viii. p. 242; Camb. Journ, Anat. and Physiol. 1871, vol. v. p. 123 ; and Joum. Linn. Soc. 

 Zool. vol. xi. p. 146. 



= L. c, p. 232. • L. c. 



