194 
BALANUS crassus* 
TAB, LXXXIV. — Fig. 2« 
Spec. Char. Oblique^ thick; valves six., obscurely 
ribbed^ smooth ; aperture triangular. 
Not so conical, thicker, and more irregular than the last ; 
the aperture is four-sided, but three of its angles are more 
acute than the fourth: its height equals the diameter of 
the base. 
This specimen, from Holywell near Ipswich, by favour 
of the kind friend to science, Mrs. Cobbold, is the best I 
have seen. At the same place are found separate valves 
and fragments, perhaps of the same species. Fig. 4 is rather 
more ribbed. Fig. 3 is smooth and destitute of ribs; ap- 
parently from being worn. The inside projections and 
pores at the narrowish base are exposed in the lower figures 
3 and 4 ; in one of them which is very thick, the bottom 
pores are elongated. Perhaps it will become of use to 
notice these parts as the progress of the yet infant knowledge 
of organic remains will point out. 
