938 Transactions of the Society. 



Xanthidium Ehr. 



18, 19. X. armatum Breb. In a slide from the United States 

 I have found two widely different forms of this fine species : — 



a. Nov. var. Wolleanum. This form greatly exceeds the limit 

 of size of European type, being nearly as broad as they are long. 

 Rather finely punctate. The average measure of several specimens 

 is long. (s. spin.) 168//, = '0066 in.; lat. (s. spin.) 104 yu- = 

 •0041 in.; lat. isthmi42/^ = -OOieSin. Fig. 18. 



^. Nov. var. Americanum. This smaller form varies much in 

 size. Scrobiculi well defined. On several specimens I could not 

 (under careful illumination) perceive any puncta. Fig. 19. Measure, 

 without smnes, long. 70-123 {x = • 0027- • 00484 in. ; lat. 38-73 //, 

 = -00149-29 in. : lat. isthmi 31-37 fx, = -00122-146 in. The 

 Eev. F. Wolle gives (Amer. Desm., p. 92) lat. 62-140 /a.. Ealfs 

 gives lat. as 94 yu., with long. 139/1,; and Eabenhorst gives lat. 

 as 95-115 /t. The specimens figured were from New Jersey; and 

 it is noteworthy that they approach in contour the European type, 

 rather than the " angular " forms figured by Wolle, loc. cit. 



20. X. hastiferum nov. sp. This form approaches one de- 

 scribed by Dr. Nordstedt from Java, as " X. antilopseum f. 

 javanica" (Alg. Mus. Lugd. Batav. p. 12, t. i. f. 21, 1880) but is 

 smaller by about one-sixth, and the central spines are comparatively 

 minute. Southern India. Fig. 20. 



Long. sin. acuL 38-5 /t = -00152 in.; lat. sin. acul. 40 /i = 

 -00157 in.; lat. isthmi 11 /* = -00043 in.; long. acul. 21 /a = 

 •0008 in. I cannot but think that this and forms allied to it 

 would be wrongly placed as varieties of X. antilopmum, as the 

 contour of cell, inchnation of spines, isthmus and sinus so widely 

 difier. 



Staurastkum Meyen. 



21. ;S^. gladiosum nov. sp. — Species with reniform segments ; 

 spines strong, arrayed in series, a few smaller ones scattered ; end 

 view triangular, with gently concave sides ; ends broadly rounded 

 with six to eight large spines at each ; sinus open, expanding rapidly. 

 Malaga, New Jersey, U.S.A. 



Long. 49 /i, = -0019 in.; lat. = long.; lat. isthmi 11-12 /t 

 = -00043-47 in. Fig. 21. This forms a unit in a series com- 

 prising Saxonicum, Brebissonii, ecTiinatum, aculeatum, pecten, 

 tridentiferum, &c. It is near to the small form of S. Saxonicum 

 Bulnheim, but is just as broad as long, and the segments are not 

 " densely aculeate," as in that species. 



22. S. spongiosum Breb. The form figured as " the more 

 frequent " one in Amer. Desm. t. xlvii. f. 5, 6, by the Eev. F. 

 Wolle is so different from the type that it would perhaps be better 



