408 DR. GWYX JEFFREYS ON MOLLUSCA OF THE [Apr. 16, 



Mus. Comp. Zool. No. 7, 1869, p. 127), " Very young specimens are 

 natter, rounded, and have a strait margin : they could scarcely be 

 distinguished from the young of Terebratula cubensis, if it was not 

 for the loop and septum seen by transparency. There is also some 

 variety of form in the old ; in some specimens the length is greater 

 than the breadth, and there is considerable diversity in the sinuosity 

 of the frontal margin." T. septata is not less variable in shape and 

 in the flexuosity of the front margin ; a young specimen which I 

 dredged in the ' Porcupine ' Expedition of 1870, attached to a branch 

 of Oculina prolifera, was mistaken by me for Terebratella spitzber- 

 gensis, having the same oval and laterally compressed outline, and 

 a similar septum visible through the shell. 



In young and half-grown specimens of T. septata, as well as in 

 other allied species, the side flanges or flaps of the loop are closed 

 by a membrane, which is removable ; the openings then appear. 

 The inner layer of the shell is microscopically and closely striated 

 lengthwise. The gradual development of the skeleton or apophy- 

 sary process, indicated by the changes which take place in the course 

 of growth, is very remarkable, and is shown in the accompanying 

 figures (Plate XXIII. figs. 1 a, b, c). Mr. Davidson and I agree 

 that the loop in T. septata, when quite young, resembles that of a 

 Megerlia, and is three times attached ; at a rather more advanced 

 age it assumes the form of a Terebratella, and is twice attached ; in 

 the full-grown state it has all the characteristics of the subgenus 

 Waldheimia, and is attached only to the hinge-plate. Mr. Friele 

 has also, to some extent, demonstrated these retrograde changes 

 in his papers above referred to. 



This species is unquestionably the T. septigera of Loven (1846), 

 and equally without doubt (so far as my opinion is worth any thing 

 in either case) the T. septata of Philippi, 1844. Seguenza, how- 

 ever, considers Philippi's species to belong to the genus Terebratella ; 

 and he has named Loven's species Waldheimia peloritana. Although 

 the skeleton represented in Philippi's figure was imperfect, there is 

 no appearance of the cross bar to which the loop is attached in 

 Terebratella, and which cross bar is not less persistent than the sep- 

 tum in broken and worn specimens of so many species of that genus 

 as well as of Megerlia. Indeed his description and figures agree as 

 closely with imperfect specimens of T. septigera, as those of his T. 

 euthyra with imperfect specimens of T. cranium. Seguenza may 

 have found in the Sicilian Tertiaries not only his W. peloritana, 

 which he now refers to T. septigera, but also a species of Terebra- 

 tella which he regards as Philippi's species. For this last-mentioned 

 species, if not known in a recent or living state, he might give 

 another name. Were not priority of publication an essential stand- 

 point for scientific nomenclature, septigera might be retained for the 

 recent species, and septata for Seguenza's fossil species of Terebra- 

 tella ; but in the absence of better data it may be more advisable 

 " quieta non moveri." W. peloritana and W.Jloridana appear to 

 be the same variety of T. septata. 



I cannot refrain from expressing my admiration of the careful and 



