84 Notes on the Ascidea Manhattensis^ De Kay, 



later in June, Their earlier or later appearance, as well as de- 

 velopment, depends on the higher or lower temperature of the 

 season. During the unusually warm summer of 1856 a great 

 many specimens were full grown — ni^ne lines to one inch in 

 diameter — as early as July 15, while commonly on the same 

 date the largest specimens measure but six lines. The animal 

 perishes, it appears, soon after the ova are ejected. 



Larvse arrive througli the summer months, and later, for 

 young specimens were found, constantly together with those 

 more or less developed or full grown. Those which arrive late 

 in the season (August and September) probably perish prema- 

 turely. 



My observations on the general and minute anatomy of this 

 species, and of some morphological changes of certain organs, 

 particularly of the branchial sac, saccus calcareus, and ovaries, 

 and on gemmation, I shall publish hereafter. 



In connection with the foregoing statements, I offer some 

 remarks on J/ammo^Hce, which Lamarck* refers to the Ascidians 

 as a sub-family, enumerating three species, and which he de- 

 scribes in the following manner: "Corpus librum, nudum, 

 ovale aut subglobosum ; apertura unica ad apicem." He says, 

 1. c, that the organization of the MaTninaricB was known so 

 little that they could be classified only provisionally ; he sup- 

 poses that, in case the body had a double envelope, " les deux 

 ouvertures, que I'on supposerait a I'interieure, viennent aboutir 

 a I'oscide unique, qui termine superieurement a I'exterieure," 

 and adds that doubtless further observations are necessary in 

 order to enlighten us in this respect. 



The literature on the Ascidians here at my disposal furnishes 

 nothing new on the subject. 



On the 16th of August, 1850, I found Mammarim of about 

 the same size of the so-called three species enumerated by La- 

 marck, the largest 1.5 lines 1., 1 line br., with one terminal 



* Hist. Nat. des Animaux sans Vertebres, torn. iii. p. 473, 1841. 



