4 JOHNS HOPKINS UNIVERSITY MORPHOLOGICAL MONOGRAPHS. 



9. SEELIGER, Dr. OSWALD. Die Entwicklungsgeschichte der socialen Ascidien. 

 Jenaischen Zeitschr. XVIII, N. Z. XI, 1-145. Taf. I-VIII. 1885. 



10. BARROIS, Dr. JULES. Recherches sur le cycle genetique et le bourgeonnement 

 de 1'Anchinie. Journ. Anat. Phys. XXI, 1885, pp. 193-207. Plates VIII-XII. 



11. SEELIGER, Dr. OSWALD. Die Knospung der Salpen. Jenaische Zeitschr. XIX, 

 573-677. Plates X-XIX. 1886. 



12. BROOKS, W. K. The Anatomy and Development of the Salpa-Chain. Studies 

 Biol. Lab. Johns Hopkins Univ. 1886, pp. 451-487. Plates XXVIII, XXIX. 



13. SEELIGER, Dr. OSWALD. Die Entstehung des Generationswechsels der Salpen. 

 Jenaische Zeitschr. XXII, 398-414. 1888. 



- 14. HERDMAN, Dr. W. A. Report upon the Tunicata collected during the Voyage 

 of H. M. S. Challenger during the Years 1873-7G. Part III. Report on the Scientific 

 Results of the Voyage of H. M. S. Challenger. Vol. XXVII, Part LXXVI. 1888. 



15. SEELIGER, OSWALD. Zur Entwicklungsgeschichte der Pyrosoma. Jenaische 

 Zeitschr., pp. 595-658. Plates XXX-XXXVII. 1889. 



16. DAVIDOFF, Dr. M. v. Unters. zur Ent. der Distaplia magnilarva Delia Valle. 

 Mittheilungen aus der Zool. Station zu Neapel, IX, 113-178 and 533-562. Plates V, 

 VI and XVIII-XXIV. 1 889-91 . 



17. SALENSKY, Prof. W. Beitriige zur Embryonalentwickelung der Pyrosoma. 

 Zool. Jahrbiicher, Band IV, 424-478. Taf. XXVI-XXVIII ; Band V, 1-98. Taf. I-VIII. 

 1891. 



18. D'KOROTNEF, Dr. ALEXIS. La Dolchinia mirabilis. Mittheilungen aus der 

 Zool. Station zu Neapel, X, 2, 1891, pp. 187-205. 



Salpa is a transparent, swimming Tunicate, and its body, Plates III 

 and IV, is, in effect, an enormous pharynx which swims through the 

 water, gulping in great mouthfuls at each contraction of its muscles. 



In shape it is subcylindrical, and its body may be compared to a 

 barrel open at both ends, so that water flows through it without obstruc- 

 tion. The mouth, r, occupies the anterior end of the barrel, and the lips 

 are infolded in such a way that they act as valves which permit the 

 water to enter between them while they prevent it from escaping, while, 

 at the opposite end of the body, the atrial aperture, g v , affords an exit for 

 it. Practically the chamber of the barrel is uninterrupted from one 

 opening to the other, for while it is divided, morphologically, into the 

 pharynx, c, and the atrium, g'", these two chambers are separated from 

 each other only by the rod-like "gill," o, which traverses the cavity on 

 the middle line. The " gill " is so narrow that it offers little obstruction 

 to the water, and there is a free passage on each side of it. 



The body is encircled, more or less completely, by muscles which are 

 placed like barrel-hoops, so that their contraction empties the barrel and 

 drives the water out through the atrial aperture, and thus propels the 



