iSO. 6] NEW MELOBESIEAE. 7 



less thin-walled, 12—25 p. long and 6 — 9 /j- broad. The cells of 

 the rather vigorously developed perithallic layer are square or roun- 

 ■ded, 4 — 7 fi in diameter, or sometimes a little vertically elongated. 



The conceptacles of sporangia much resemble those in L. 

 ■mesomorphum, 400—600 fi in diameter, not sharply defined but 

 sometimes slightly flattened in the central parts. They frequently 

 grow down into the frond. The sporangia are four-parted, about 

 120 /■>- long b}^ 60 ;j-, generally with enduring interwalls. 



The present spedes has been gathered on the coast of Bermuda, 

 herb. W. G. Fa r lo w, no. XIII. 



L. fumigatum Fosl. mscr. 



Thallus crustlike, of indefinate shape and extent, up to about 

 4 mm. thick, with crowded, small wartlike excrescences. Con- 

 ceptacles of sporangia 250 — 300 // in diameter, slightly prominent 

 and frequently depressed in the central parts. Sporangia two-parted, 

 80—100 p. long by 30-50 t a. 



The species sticks to shells. In the thickest part the crust is 

 about 4 mm. thick, decreasing towards the rather thin peripherical 

 portion. The surface is uneven, provided nearly everyvvhere with 

 rather densely crowded, small, wartlike or irregular excrescences 

 which frequently are 1 — 2 mm. in diameter. 



With reference to structure the feebly developed hypothallus 

 is composed of up to 22 >j. long and thinwalled cells, frequently 

 however shorter, and about 6 \i thick. It sends forth perithallic 

 but rather irregular rovvs the cells of which are square or rounded, 

 4—7 fi in diameter, or a little vertically elongated, occasionally up 

 to l 1 1 2 times longer than broad, or up to about 12 fi long. 



The conceptacles of sporangia are scattered or somewhat 

 crowded almost in any part of the crust, partly scarcely raised 

 above the surface of the frond, partly and more frequently a little 

 prominent and disc-shaped, at length nearly always a little depressed 

 in the central parts. The roof is traversed by about 20 muciferous 

 canals. In the examined conceptacles I only met with two-parted 

 sporangia (and a solitary three-parted), partly with enduring inter- 



