EMBRYOLOGY OF TEREBRATULINA. 261 



seen between the embryo Brachiopod and the free embryo of Pedicellina, described by Van 

 Beneden, 1 though the development of parts within a ccenoecium, and the formation of stat- 

 oblasts are features quite unlike the Brachiopod. A roundabout relation might possibly be 

 insisted upon through the Rotifera, in their winter ova. 



After this paper had been made up into pages, Mr. Alex. Agassiz called my attention to 

 the fact that Prof. John M c Crady had published in the Proceedings of the Elliott Society of 

 Natural History of Charleston, S. C., a notice of a larval Brachiopod. 



After a fruitless search among the libraries of Boston for a perfect set of the Proceedings 

 of this Society, I learned that within a week Mr. M c Crady had made his home in Cambridge, 

 having recently become connected with the Museum of Comparative Zoology. From him 

 I learned that the original description and drawing was presented before the Elliott Society, 

 at its meeting June 15th, 1860, but, owing to the war, had never been published by the 

 Society. In the destruction of Columbia, S. C., by Sherman's Army, Prof. M c Crady not 

 only lost his valuable library, but all of his scientific records, drawings and notes. After this 

 irreparable loss, he drew up from memory a description of this Brachiopodan larva, and 

 now generously allows me to make free use of this valuable manuscript,, which contains the 

 first and only observations on a larval Lingula ever made. 



The creature in question was found by him either late in the fall of 1859, or in the 

 spring of 1860, he cannot now remember which. It was found off Sullivan's Island 

 in Charleston Harbor. The following is quoted from his manuscript. 



" 1st. The larva is a free swimming animal. 



" 2d. Its means of locomotion are large vibratile cilia, clothing the cirri of the arms, 

 precisely as in Bryozoa. 



" 3d. It was provided with a bivalve semi-transparent horny shell, recalling the shell of 

 Lingula, but with no trace of a foot stalk." (Mr. M c Crady adds hi pencil that the form of 

 the shell was flattened, and more ventricose than that of adult Lingula.) 



" 4th. In motion the valves were opened just enough to allow free play to the ciliated 

 cirri of the arms, which (i. e., the cirri) was thrust out beyond the shell rim. 



" 5th. The arms were never extended beyond the shell rim, but just within and along 

 their margin. 



" 6th. The opacity of the body was such, that added to the cloudy semi-transparency of 

 the horny shell, it was impossible to make out other details. 



" 7th. When the larva ceased swimming, the arms and their cirri were retracted, the 

 valves closed, and the animal sank to the bottom." 



By comparing the above description with that of Dr. Fritz Miiller's description, given in 

 the first part of this memoir, the closest similarity will be observed between them in their 

 general appearance, their mode of swimming, and even to the manner in which, when at 

 rest, they close their shells and sink to the bottom of the vessel in which they are confined. 

 Mr. M p Crady assures me he has never seen Miiller's description of the larval Discina. 



It is interesting to remark that nearly at the same time, these two naturalists should make 

 the first observations ever made on the embryology of the Brachiopods, if we except the 

 very brief notice of Oscar Schmidt. 



1 Hist. Nat. du genre Pedicellina. Mem. AcaVl. Royal de Belgique. Tome xix. 



MKMOIR9 B09T. 8OC. XAT. HIST. VOL. II. 66 



