REPORT ON THE RADIOLARIA. 1321 



and bear three serrated edges. Thorax three-sided pyramidal, spiny ; its three edges prolonged 

 at the girdle into three stout, triangular, prismatic wings of the same length, little curved. 

 Abdomen short, cylindrical, with wide open, truncate mouth. Pores irregular, polygonal, roundish. 



Dimensions. Length of the three joints, a 0'02, b 01, c 0'06 ; breadth, a 0'03, b 014, c 01. 



Habitat. North Pacific, Station 244, surface. 



17. Pterocorys zittelii, Haeckel. 



Pterocyrtidium zittelii, Biitsclili, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. pp. 531, 540, Taf. 



xxxiii. figs. 28, a, I). 



Shell thin-walled, rough, with two slight strictures. Length of the three joints = 2:5:7, 

 breadth = 3:5:5. Cephalis hemispherical, armed with a very large, prismatic, vertical horn, which 

 is half as long as the shell, and at its base surrounded by several (three to five) shorter, upwardly 

 diverging horns. Thorax campauulate, in the upper half with three short, downwardly diverging, 

 conical wings. Abdomen subcylindrical, with wide, truncate mouth. Pores small, subregular, 

 circular. 



Dimensions. Length of the three joints, a 0'02, b O'Oo, c 0'07 ; breadth, a 0'03, b 0'05, c 0'05. 



Habitat. -Fossil in Barbados. 



18. Pterocorys macroptera, n. sp. 



Shell thin-walled, smooth, with two slight strictures. Length of the three joints =1:3:2, 

 breadth =1:4:3. Cephalis hemispherical, armed with two larger and six to eight smaller, conical, 

 divergent horns of different lengths. Thorax three-sided pyramidal ; its three edges prolonged into 

 three very large diverging wings, which are slender, three-sided, prismatic, and nearly twice as long 

 as the shell. Abdomen short, cylindrical, with wide, truncate mouth. Pores irregular, roundish, 

 in the middle part of the shell (on both sides of the girdle) much larger than in the upper and 

 lower part. 



Dimensions. Length of the three joints, a 0'03, b 0'09, c O'OG ; breadth, a 0'04, b 012, c 01. 



Habitat. South Atlantic, Station 335, surface. 



Genus 583. TJieopilium, 1 Haeckel, 1881, Prodromus, p. 435. 



Definition. T heopilida (vel Tricyrtida triradiata aperta) with three lateral ribs 

 enclosed in the wall of the thorax, without free lateral or terminal appendages. 



The genus Theopilium differs from all the other Theopilida in the absence of free 

 external appendages ; it has neither lateral wings nor terminal feet, but three divergent 

 ribs are enclosed in the wall of the thorax. It agrees in this character with the Dicyrtid 

 Lamprodiscus, and may be derived directly from this by development of an abdomen. 



1 Theoj)Uium=T)i\'ine hat; Qios, irfatoy. 

 CHALL. EXP. PART XL. 1886.) Rr 166 



