54 AMERICAN JOURNAL 



1. Relations between the coecal prolongations of the mantle in 

 Terebratula and a similar character in the test of Crustacea. 

 Resemblance between the polygonal cells in the shell of a young 

 Discina and a similar feature in certain lower crustaceans. The 

 scale-like structure of the test of ldotcea like the scale-like structure 

 of Lingula. 



These characters are too vague to meet, and are his- 

 tological and not systematic in any case. Were they sus- 

 tained as correct they would in no way affect the question. 

 What, it may be asked, is the " scale-like structure of Lingula ?" 

 Dr. Carpenter records nothing of the kind in his admirable re- 

 searches into the structure of the shells of the Brachiopoda. 



'1. The skin of Nereis has similar punctures or dots, as seen 

 in Terebratula and the peduncle of Lingula. 



The u porenkanale" are coecal tubes, opening outwardly, 

 closed at their inner end, and lined with an invagination of the 

 external cuticle. (See Claparede ante, and also in Recherches 

 sur des Annelides, Geneva, 1869, p. 14.) The punctures of 

 the shell in Terebratula are precisely the reverse, being lined by 

 outward prolongations of the mantle from the inside, and coecal 

 at their outer extremity. I have failed, with the most careful 

 search and high powers, to discover any punctures on the pedun- 

 cle of Lingula Murphiana and L. Mans. It should be remem- 

 bered that when Prof. Morse speaks of Lingula, in most cases 

 he refers to a species of Grlottidia (Cr. pyramidata, IStm.) 



3. The shell of Discina chitinous and that of Lingula, phos- 

 phatic rather than cretaceous. 



The fact of such differences existing between two nearly allied 

 genera is sufficient proof that they are of little systematic value, 

 even if chemistry were allowed to have any bearing on systema- 

 tic classification, which is more than doubtful. 



4. Valves of all Brachiopods, dorsal and ventral, a strong 

 articulate character. 



The first statement is almost certainly an error (cf. ante), and 

 many, if not most. Articulates are without ventral plates. (Cf. 

 Marey, Lect. on Flight in the Animal Kingdom, with regard to 

 Insects, and any work on the Cypridian Crustacea.) 



5. Horny setce entirely absent in the Mollusca, and peculiar 

 to the ivorms. 



The first statement was refuted in my first paper on the Bra- 



