146 M. O. A. L. MORCH's review of the VERMETIDiB. [April 9, 



cealed, and it is then exceedingly difficult to decide with certainty 

 whether the shell is the production of an Annelid or of a Molluscous 

 animal. 



If the shell is formed of a solid matter strongly sculptured with lon- 

 gitudinal grooves or scales, or of a brownish colour, it is certainly 

 formed by a Vermetus ; but if the shell is of a soft earthy matter, 

 feebly longitudinally grooved, it is doubtful to which subkingdom 

 it belongs. 



The shells of the Serpulidee have an anal opening (except the 

 genus Cymospird), and appear only to be composed of two layers, 

 the VermetidcB having three. 



There is a striking analogy between the Vermetidce and Ostreidce 

 in respect of colours, sculpture, and growth. As in the latter family, 

 the sculpture of the Vermetidce is much influenced by the bodies to 

 which they attach themselves, the surface often showing the cast of 

 the sculpture of a coral * or another shell. 



I have convinced myself by the comparison of numerous specimens, 

 chiefly o{ Siphonium nebulosum and Vermetus decussatus, Gm., that 

 one and the same species may vary, from being strongly grooved and 

 scaly to being quite smooth and polished. 



The form and growth are not less variable ; the same species being 

 found nearly regularly spiral, top-shaped, planorbiform, or as a nearly 

 straight tube. The same species is sometimes affixed and solitary, 

 sometimes free and agglomerated, imbedded in mud (^Spiroglyphus 

 glomeratus, Biv.). Some species {Siphonium nebulosum, Dill.) are 

 affixed during the greater part of their lives, and seem then, like 

 CcEcum, to "decollate" the shell and live afterwards free in the mud ; 

 perhaps this may have relation to the sexual functions f. 



The thickness of the shell may vary from being thin and nearly 

 pellucid to being very thick and incrustated ; if the shell be laterally 

 affixed, the dilated angular sides are filled out with a solid calca- 

 reous mass (Chenu, lUustr. pi. 2. f. 2). 



In the interior of several species {Petaloconchus) are found some 

 very long lamellae, generally regarded of generic value. I have 

 reason to think that these lamellae are dissolved with age, like the 

 teeth of some species of Pupa % ; or perhaps they are of a sexual na- 

 ture, like the interior cup of Beguina {Thecalia) concamerata, Chem., 

 from the Cape of Good Hope, which is said to contain the fry. 



Daudin and Marcell de Serres thought they had discovered a 

 generic character in the habit possessed by some Wormtubes of bur- 

 rowing in other shells. Although this character is more developed 

 and constant in some species than in others, it is scarcely of specific 

 value, and is common to nearly all young Vermeti. Vertically grow- 

 ing species often show the same dissolving power in removing parts 



* Seba, ' Thesaurus,' vol. iii. t. 93. f. 9, and Ostrea cumingii, Dkr. in Philippi 

 Abbildungen, t, 1. 



t Siebold (Lehrbuch der vergleich. Anatomie, p. 355) denies the presence of 

 an exterior penis ; but Riippell (Atlas, 1. 11. f. 3) has figured a species with an 

 exsert male organ. It appears that the large fusiform cells containing unde- 

 veloped spermatozoids (Siebold, I. c.) are Spermatophores. 



X V. Martens, Ueber Pupa Wienlandi Kur. Mai. Blatter. 1859, p. 209. 



