Natural Sciences of Philadelphia during the Ymr 1821-. 3.3;! 



Mollusca. — This department has already been enriched by 

 valuable papers from Mr. Lesueur ; and in the last year he 

 has added to his former observations, by his " Description of 

 a new species of Ceph alopod a, oi' the genus Loligo." The Lo- 

 ligos have been so fully studied, and the number of their spe- 

 cies so much increased by this gentleman, that he may almost 

 be considered as having appropriated to himself this genus of 

 Lamarck's. His last conmiunication makes us acquainted 

 with an inhabitant of our buy, which has received from him 

 the name of L. brevipenna. The individual which our author 

 observed, appeared to him to resemble the genus Sepiola more 

 closely than any other Loligo which he had seen. In the same 

 communication Mr. Lesueur adverts to the fact of his having, 

 in the year 1814, observed a species of Sepiola in the British 

 Channel. This will prevent our erroneously drawing an infe- 

 rence of their non-existence in those waters, from the statement 

 made by Mr. Blainville that he had never met with them there. 



Vermes. — Mr. Lesueur has described " three new species of 

 parasitic Vermes, belonging to the Linnaean genus Lernaa" 

 which he refers to Mr. Blainville's genera Lerneocera and 

 Lerneopenna. In order that two of his species, the cruciata 

 and radiata, may be included in the former genus, its generic 

 characters must be extended so as to admit species whose arms 

 are simple and not |jranclied. Should this modification of the 

 Lerneocera not be admitted, then Mr. Lesueur's two species 

 will constitute a new genus, for which he suggests the name of 

 Lerneceniciis. The third species which he describes is the 

 Lerneopenna Blainvillii which inhabits the Exocetus volitans. 



Zoophytes. — The same able naturalist has contributed to this 

 department by his investigations of the Holothuria, from the 

 island of St. Bartholomew. In his classification of these ani- 

 mals, Mr. Lesueur has been led to prefer divisions founded 

 upon modifications in the form and structure of the tentacula, 

 to those which depend upon the correspondencies of form and 

 disposition of feet, as had been adopted by Messieurs de Blain- 

 ville and Cuvier. 



Availing himself of the two divisions adopted by Mr. de 

 Lamarck, our author suggests that those species vi'hich have 

 pinnated tentacula should he placed in a distinct division. 

 Of these, Mr. Lamarck was acquainted with only one species. 

 Mr. Lesueur's descriptions include four species with cylindri- 

 cal tentacula [H. obscura, agglutinata, muculata, and fasciata\ 

 two species with arborescent tentacula {H. lapidtfera and 

 Briareus), and two with pinnated tentacula (//. hydriformis 

 and viridis). 



In addition to the above communications on zoology, a paper 

 Vol. 66. No. 331. Nov. 1825. Y y was 



