No. 7] REMARKS ON MELOBESLE IN HERBARIUM CROUAN 1 1 



herbarium Bornet I have seen a fevv specimeiis distributed by 

 Crouan himself. One of these forms a thin crust on porcelain, 

 aboLit 1.5 cm. in diameter and rather irregular in outline. The crust 

 is nearly smooth, with entire or crenulate margin. Three other 

 specimens are attached to fragments of shells of mollusks, and one 

 of these much approaches Lithothamnion læve in habit, They are 

 older and in part more uneven than the above mentioned specimen, 

 but otherwise agreeing with this. 



The species also grows on shells of Balanides, rocks, a rather 

 loose conglomerate of sand and shells, and once I have even seen 

 it attached to Lithothcminion Lenormandi. Thus it sticks to quite 

 different substrata, and, therefore, much varying in habit. Some- 

 times it reminds one of a young Goniolithon 'papillosum sometimes 

 certain forms of G. Notarisii, but, on the other hand, rather ap- 

 proaching certain forms of L. Lenormandi in habit when growing 

 on a loose substratum. In the latter case it forms small, more 

 or less confluent and rather irregular crusts, here and there stret- 

 ched over one another, and then quite different in habit from spe- 

 cimens growing on a smooth substratum. The latter form passes 

 into the below mentioned f conjinis. However, also on a smooth 

 substratum I have once seen a new crust stretched over a sub- 

 jacent and even over a conceptacle of the latter. 



The crust attains a thickness of about 400 jj., with up to 8 

 layers of cells. It is much varying also in structure. The basal 

 cells are commonly high and more or less curved, 50 — 100 ji, or 

 now and then shorter. In the upper layers the cells are also much 

 varyiny, or 20 — 70 p- long. On the other hand, they are rather 

 •uniform in breadth, frequently about 12 jj.. 



The conceptacles of sporangia are prominent, subhemispheric 

 ■or subhemispheric-conical, frequently 350 — 450 p- in diameter seen 

 from above. The sporangia are bisporic, 70 — 120 p- long and 

 40—60 p- broad. 



The present species is known from Brest (Crouan), Le Croisic, 

 Loire inférieure (Bornet), Gap Antifer (Debray), Cherbourg (Le 

 Jo lis), Berwick-on-Tweed (Ba t ters), and the west coast of Ireland, 

 where I have coUected specimens however not yet exactl}^ determined. 



