Identity of Pholadidea papyracea and Pliolas laniellata. 9 



and only consist in the circumstances, that during the summers 

 of 1848-9 I sedulously for several weeks examined the Pho- 

 lades, both in situ and in the closet, when after a careful inves- 

 tigation I arrived at the same conclusions with respect to the 

 boring agents of the bivalves as Mr. Hancock ; and I have the 

 notes of them now by me, written before Mr. Hancock's publi- 

 cation, which I intended to lay before the public ; that gentle- 

 man has anticipated me, the whole merit is his, and I cordially 

 apply to him the motto, " Palmam qui meruit, ferat." I will now 

 state some facts which perhaps have escaped Mr. Hancock's at- 

 tention, corroborative of his positive discovery. 



I revert for a moment to the consideration of the identity of 

 Pholadidea papyracea and the Pholas lamellata of authors, on 

 which point Professor Forbes and Mr. Hanley, in the ' British 

 Mollusca/ have concurred, having in some measure relied on my 

 authority communicated many years ago. The investigation in 

 the last summer (1848) was undertaken by me both with the 

 view of making an attempt to discover the terebrating powers of 

 the Acephala, particularly of the Pholades, and for further proofs 

 of the identity of the two forms styled by authors Pholadidea 

 papyracea and Pholas lamellata. 



In the course of my examinations I was startled by the great 

 variations in the organs of the two forms of this Pholas, which, 

 twenty years ago, when I first examined this species, appear not 

 to have so rigorously excited my notice ; doubts arose in my 

 mind, that I might be wrong in my former determinations of 

 identity, and I wrote to Dr. Battersby to express them to him 

 and Mrs. Griffith, both of Torquay ; the latter a lady naturalist, 

 who has taken great interest in this question ; but in the present 

 summer of 1849, after a continued investigation of fourteen 

 weeks, my doubts were dispelled, and I stated personally to Dr. 

 Battersby, that after a careful review of all the evidences that pre- 

 sented themselves, I reverted to and relied on my original deter- 

 minations of identity of the two forms of Pholadidea papyracea. 



This change of opinion arose from the observation that in the 

 adult Pholadidea papyracea, the mottled appearance of the belly, 

 so dissimilar to that of the form Pholas lamellata, was due to the 

 extension of the reproductive membranous organs of the ovarium 

 and the spermatozoa, occupying the space usually appropriated 

 to the foot, which I found had disappeared. This anomalous 

 appearance excited my attention, and the reflection that with 

 nearly absolute cceteris paribus, in the generalities of all the Pho- 

 lades, there was no substantial reason why one species should 

 always be deprived of the foot, when all the others possessed that 

 appendage, and as I had come to the conclusion, that it was 

 the boring instrument, I felt assured that this anomaly was only 



