KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 34. \:o 8. 59 



the eyes. Bu1 ra how far there ever bas existed such prismatic lenses, now changed, we 

 have no evidereee definitelj to ascertain, but the probabilitj seems to be greaf thal this 

 was the case. 



Merans gigas Holm. 



Pl. IV figs. .",1 37. 



The maculse in this as well as the other [llaeni are so faintly elevated and so in- 

 conspicuous thal the greatest attention is necded to lind them. 



The maculse are elongated, narrow, elliptic on the same leve] and paralle] with the 

 straighl anterior margin of the hypostoma. A cast of the left macula is pitted l>\ nu- 

 rnerous marks of the lenticular globules of the surface, fig. -'!7. In the cephalic eye the 

 prisms are scen transluceni beneath the cornea. Near the superior börder thej are larger, 

 fiar. 34, almost the double si/c of those near the inferior börder, fiff. .'!•">. 



[llsenus sphaericus Holm. 



P] IV tigs. 42, 43. 



Comes near to the previous speeies. The globules on the surface of the elliptic 

 maculae are not, however, spread över the entire macula, leaving only a narrow börder 

 all around free. 



The lenses in the cephalic eyes fig. 42 are globular as scen on the surface, alike 

 those <>f the maculae. 



Illaenns Roemeri Vollborth. 



Pl. IV figs. 38—41. 



The maculae lic on elevated tubercles and are of a stränge shape, being sharpelv 

 pointed outwards, rounded inwards. That in fig. 39 is still more peculiar with a narrow 

 stripe on the interiör and upper margin. The lenses are larger and more distinct than 

 in any other speeies of this genus. 



Bcside the speeies now mentioned we have also observed hypostomas with maculae 

 in Illaenus laticlavius Eichwald from Estland, in Illasnus Linnarssoni Holm, and in an 

 nnnamed speeies from Dalecarlia figured without maculse by Di-. Holm in his memoir on 

 the Illaenidae pl. III fig. 22. We have not seen any lenses on the macula3 of these three 

 len ses. 



Lichas Da 



LM AN. 



We have not been able to find any notice about the exceptional maculoä of this 

 genus. There is only a tigure of the hypostoma of Lichas hylteus Hall Pal. of X. York 

 vol. VII pl. XXV fig. 5 which would seem to show a pair of narrow, oblique maculae, 

 but these are quite without resemblance with the maculae of the true Lichas. 



