200 Dr. J. .E. Gray on a new genus and species of SeaL 



'T'Y'^"r''Trn.'^'^-'^ "^iT^^' Pirate X. •*-»■• •♦t^«>r» »j fta^i^i\ffitYr^»y 



t'ig. 7. Rectal branchiae of JEshna grandis, after M. Leon Dufour : 

 C, a, orifices in the rectum of the branchial folds (A) ; a, dilated 

 extremities of the tracheae. 



Fig. 8, Head, tail, digestive system (c?), tracheal {h) and branchial {g) 

 systems, hepatic vessel (e), of Agrion Puella, after M. Dufour. 



Fig. 9. A small piece from the parietes of the intestine of the Cockroach, 

 showing the extreme distribution of the trachea (a). The blood- 

 current accompanies the tube only as far as i. The trachea then 

 describes a true network (e, c, d) of membranous tubes. In the 

 meshes the glandular cells (/, g) are placed. A clear space inter- 

 venes between the trachea and glandular cells in which the nutri- 



^^l^l 1)')' tive fluids, without the corpuscles, may probably move. 



f'ig, 10*. A small piece of the wing of the Cricket drawn under a high 

 power : a, a large trachea in the centre of the nervure or chan- 

 nel, surrounded by two opposed currents of blood {b,c); i, larger 

 branches; d, e,f, small terminal tracheae, entering alone, without 

 coincident, blood-currents into the scaly interval ; j, long, slender, 

 wavy tracheae floating in the fluid j g, blood-corpuscles, travelling 

 in the channel b. 



Fig. 11. One of the tracheae from the scaly intervals between the nervures 

 of the wing of the Cricket, showing the mode in which it termi- 

 nates (b) between the scales d. 



jHg. 12. A minute portion of walls of the stomach of the Cockroach, show- 



0': ing the wavy manner (c,/) in which the membranous capillary 



,^1;^ tracheae are distributed around and between the ultimate glan- 



dular elements ; at e, the current of the blood, as traced through 

 the blood-corpuscles, tm-ns back : «, large spiral tracheae. 



Tl-g. 13. A small portion of a spiral trachea, exhibiting the coats under the 

 action of acetic acid : a, outer coat raised, indented like the spi- 

 ral (b); c, the internal or mucous coat. 



Fig. 14. A piece of voluntary muscle, representing the manner in which 

 the tracheae enter the substance of the muscle. 



Fig. 15. One of the above tracheae traced into the substance of the muscle ; 

 a, b, e, network of ultimate membranous tracheae as they are dis- 

 tributed between the ultimate muscle-fibres — the latter being 

 omitted. 



[To be continued.] 



XIX. — Description of a new genus and species of Seal (Heliopboca 

 Atlantica) /rom Madeira. By Dr. J. E. Gray, E.R.S., Y.P.Z.S. 



''^- &c. 



Some montlis ago Mr. MacAndrew most kindly procured for nie 

 the skin of a Seal from the island of Madeira. A careful exami- 

 nation of it convinced me that it was a new species, most allied 

 to Phoca burbata of the North Sea, but yet quite distinct from 

 it. Mr. MacAndrew after considerable trouble at length ob- 

 tained for me another skin of an older animal with its skull, 

 which proves that it is not only a new species, but presents a 

 new combination of characters such as 1 believe entitle it to be 



