On the Blood-corpuscles of the Cyclostomata. 231 



base of front, tlie ocelli also surrounded with fuscous ; the 

 head is also mottled with very pale ochraceous, and the eyes 

 are dark castaneous. Pronotura with the margins pale ochra- 

 ceous, an indistinct central fascia margined with ochraceous, 

 with an obscure castaneous spot on each side, and four oblique 

 incisions on disk, two on each side of central fascia. Meso- 

 notum with two obscure central obconical spots margined with 

 greenish, the lateral margins and the basal cruciform eleva- 

 tion also of the same colour. Abdomen with the stigmata 

 and the segmental margins castaneous. Body beneath ochra- 

 ceous ; apex of the rostrum, basal and apical annulation to 

 tibiffi, apices of the tarsi, and penultimate abdominal segment 

 castaneous. Tegmina pale hyaline, with talc-like reflexions ; 

 venation alternately ochraceous and fuscous ; costal membrane 

 and a small costal spot at base of upper ulnar area ochraceous, 

 basal claval area greyish opaque ; transverse veins at the 

 bases of the second and third apical areas slightly infuscated. 

 Wings as tegmina, but unspotted. 



^ . Long. excl. tegm. 25 millim. ; exp. tegm. 65 millim. 



Hah. Sumatra [Forbes], March. 



The body is moderately robust ; the abdomen broad, nar- 

 rowed at apex. The lateral margins of the pronotum are 

 slightly sinuated. The face is broad and tumid, with a central 

 and very obscure levigate carina, but not sulcated ; transverse 

 ridges not extending to apex. Rostrum just passing the 

 posterior coxae. Opercula very small, obliquely rounded, not 

 reaching the basal segment of the abdomen. 



This is one of a series of small species of Pompoma found 

 in the Eastern islands. It is probable that the colour is, or 

 often is, green, and not ochraceous, during life. 



XXIV. — On the Blood' corpuscles of the Cyclostomata. 

 By Professor D'Aecy W. Thompson, Dundee. 



It is commonly stated in the text-books, for example in 

 Huxley's 'Anatomy of the Vertebrata' (p. 100), that the 

 blood of the Cyclostomes differs from that of all other fishes 

 in the round instead of oval shape of its red corpuscles. 

 Gulliver, on whose authority most of the text-book statements 

 concerning the size and shape of blood-corpuscles rests, says, 

 in his edition of Hewson's works (p. 234), "In the Cyclo- 

 stomes the corpuscles are of the same figure as those of Man, 

 and only slightly larger." Accordingly I was more than a 

 little surprised, on examining some living Myxince lately, to 



