Mv, F. E. Bedclard on Striated Muscles in Echinida. 429 



municated to the French Academy (' Comptes E.endus/ 1881, 

 Feb. 7, p. 308), and this was translated into the Ann. & Mag. 

 Nat. Hist. (vol. vii. ser. 5, 1881, p. 275). The research was 

 completed at j\I. de Lacaze-Duthiers's laboratory at RoscofF, 

 and a notice of the main results was published, simultaneously 

 with the detailed communication to the Royal Society of 

 Edinburgh, in the ' Archives de Zoologie Experinientale ' 

 (tome X. " Notes et Revue," p. xvii). In the ' Transactions ' 

 paper the muscles of the pedicellaria3 — those which serve as 

 adductors of the valves — are figured (pi. xx. fig. 2), and the 

 fact that they are striated is noted in the text (p. 387) of that 

 paper as well as in the other communications on the subject. 



Since that was written 1 have had the opi)ortunity, at the 

 Zoological Station of Naples, of studying the structure of the 

 pedicel larire in other Echinoids, and have found, as might be 

 expected, that there is an entire similarity. In Echinus melo 

 and Echinus hrevisjjinosus the muscles of the " ophiocepha- 

 lous " pedicelhu-ia3 are striated ; in tlie former species I also 

 observed a striation in the " gemmiforra " pedicellaria^, which 

 Mr. Geddes and I were unable to prove in the case of E. 

 sphcera. In Toxopneustes lividus both the " tridactyle " and 

 " ophiocephalous " pedicellarias contain striated muscles. 

 Finally, in a species of Arbacia which is very abundant at 

 Naples the " ophiocephalous " pedicellariai show striations. 

 The above statement must not be understood to imply that 

 the other forms of pedicellaria? not mentioned — for example the 

 " gemmiforra " pedicellaria3 of Echinus hrevispinosus — are 

 without striated muscles ; I simply take this opportunity of 

 noting a few observations made by me at Naples in the year 

 1881, which are too fragmentary to be worth publishing in 

 detail. 



It is not always possible to detect the striations in the 

 pedicellaria-muscies ; and the failure of previous observers to 

 detect them is no doubt due to imperfect methods of preser- 

 vation. Mr. Murray kindly allowed me to examine a num- 

 ber of the ^ Challenger ' Echinoidea, with a view to an inves- 

 tigation on the comparative anatomy of the pedicellariai ; in 

 no instance, however, did I succeed in seeing any striation on 

 the muscles, which is probably owing to the fact of their 

 preservation in alcohol. The reagents which Mr. Geddes and 

 I found to be best for displaying the striation are mentioned 

 in our paper. 



In our paper on Echinus sphcera the existence in the ophio- 

 cephalous pedicellarige of certain remarkable skeletal struc- 

 tures was referred to ; these have the form of flat plates of 

 elastic tissue formed of a number of about equally-sized 



