ON TETRACOTTLE PETROMYZONTIS. 



497 



sketch of it. I hope, therefore, that the accompanying figures 

 and this description may help to gain for Tetracotyle 

 petromyzontis the interest it merits. 



E/EFERENCES. 



Brandes, G.— "Die Familie der Holostomiden," 'Zool. Jahrbiicher,' Ab. fiir 



Systematik, v, pp. 549—604, pi. xxxix— xli. 

 Braun, Max.— "Zur Eutwickelungsgeschiclite der Holostomiden," 'Zool. 



Anzeiger,' xvii, pp. 165 — 167. 

 GooDSiR, H. S.— 'Transactions Roy. Soc. Edinburgh,' xv, p. 561, 1844, and 



' Proceedings Roy. Soc. Edinburgh,' i, p. 466. 

 Gulliver, G.— ' Quart. Journ. Micr. Sci.,' Nov., 1872. 

 MiJLLER, J.— ' Vergleichende Anatomic der Myxinoiden,' Berlin, 1835, 

 Nordmann, a.—' Mikrographische Beitriige zur Naturgeschicbte der Wirbel- 

 losen Thiere,' Berlin, 1832. 



EXPLANATION OF PLATE 39, 



Illustrating Mr. A. W. Brown's paper, "On Tetracotyle 

 petromyzontis." 



Key to the Lettering. 



at. Atrium of the glandular adhesive body. ex. b. Excretory bladder. 

 ex. fi. Excretory pore. ex. v. Main vessel of the excretory system, ffl. b. 

 Glandular adhesive body. gl. c. Gland-cells, int. Intestine. /. s. Lateral 

 adhesive organ, m. Mouth, muse. Retractor muscles of the lateral adhesive 

 organ, n. c. Nerve-cord. (es. (Esophagus, or. s. Oral sucker, p. v. Poste- 

 rior lateral branch of main excretory vessel, t. Tail region of body. tub. 

 Tubules leading from gland-cells to lateral adhesive organs, t. v. Terminal 

 vesicle of the excretory system, v. s. Ventral sucker. 



Fig. 1.— View from the ventral surface of the entire animal. Leitz, cc. 1, 

 obj. 5. 



Fig. 2.— Outline sketches, showing changes of shape at four consecutive 

 ghort intervals. 



