200 Mr. J. Miers on the Tribe Colletieffi. 



to attain a larger size in our own seas than in the south of 

 Europe : viz., Murex corallinus, Lachesis minima, Rissoa stri- 

 atula, Donax politus, Avicula Tarentina, Galeomma Turtoni, and 

 Trochus striatus. These are, according to the late Professor 

 Edward Forhes, some of the principal representatives of the 

 " Lusitanian " type. 



To these may be added species of Artemis, Cylichna, Mactra, 

 Mangelia, Nassa, Natica, Nem-a, Pecten, Pectunculus, Syndosmya, 

 Tapes, Tellina, Tornatella, Trochus, Twritella, Venus, and proba- 

 bly of every other genus which is common to the European seas. 



I have purposely omitted any of the species which Mr. 

 M'Andrew may consider as " Arctic," " Boreal," or " Celtic," 

 although I apprehend such geographical distinctions have no 

 foundation in fact or in nature. 



The difference between Mr. M'Andrew and myself (or the 

 error into which one of us has fallen) may have arisen fi'om our 

 respective collections being better furnished with specimens of 

 the shells which each has had greater opportunities of procuring ; 

 and it is to be hoped that further experience will show which of 

 our conclusions is correct. 



XXIII. — On the Tribe Colletiese, with some Observations on the 

 Structure of the Seed in the Family of the Rhamnacese. By 

 John Miers, F.R.S., F.L.S. &c. 



[Continued from p. 95,] 

 In regard to the general structure of the flower in the Colle- 

 tiece, there is little to add beyond what we find recorded on the 

 subject ; but it may be remarked that the lobes of the calycine 

 border in that tribe, as in others of the Rhamnacea, have a 

 prominent keel along the middle of their internal face, which 

 terminates below the apex in an elevated callous gland, con- 

 nected with two other raised lines that run along the border. 

 These medial keels and glands have been supposed by some to 

 be so many sterile stamens ; but Brongniart, with more truth, 

 considers their appearance to be the result of the impression 

 left upon the soft fleshy lobes of the calyx, while in aestivation, 

 by the indentation of the enclosed petals and stamens : that 

 such is the real cause, is shown in the instance of Gouania, 

 where a similar carinal prominence exists in the calycine lobes, 

 and, in addition, at the base of each keel is seen an acute scale, 

 which is really the rudiment of an abortive stamen. Similar 

 impressions are frequent in many other families where the floral 

 envelopes have a valvate aestivation. We meet with another 

 point of structure in the Colletiea, which, as far as I am aware, 

 has not been noticed by botanists : I refer to the peculiar deve- 



