4 PROCEEDINGS OF THE NATIONAL MUSEUM vou 66 



measurements: maximmn length, iy.2 cm.; maximum breadth, 5.1 

 cm. ; and maximum depth, 4 cm. 



The pedicle valve is strongly incurved in its apical portion. An- 

 teriorally the valve widens more rapidly than in H. insignis, attain- 

 ing a maximum breadth a])proximately equal to the length. This 

 relative proportion of length to breadth holds in moderately small 

 as well as adult individuals. The cardinal slopes are well defined, 

 but relatively smaller than in H. insignis. The pedicle valve is 

 moderately and e^'enly arched. Although larger than the brachial 

 valve there is not the striking disproportion in size between the 

 valves that is characteristic of H. insignis. The brachial valve is 

 strongl}^ incurved in its apical portion. In neither valve as seen is 

 a well defined median sinus developed, although there is a slight 

 median flattening and a well marked flexure of the anterior margin 

 of the valves. 



The shell is thick and the surface is marked by fine concentric 

 growth lines. 



n. rotundus may readily be distinguished from H. hisignis by its 

 relatively greater breadth, the lack of sharply defined median sinuses 

 in the valves (although this character is developed in a larger 

 crushed specimen that is doubtfully referred to this species) , and by 

 the less highly arched and relatively smaller pedicle valve. 



Horizon and locality. — The species is known only from the Brook- 

 sina-bcaring limestone scries on the north shore of Heceta Island, 

 Southeastern Island. 



Holotype.—Csit. No. 70230, U.S.N.M. 



HARPIDIUM LATUS, new species 



Plate 2, figs. 1-0 



In the Brooksina alaskensis zone on Kosciusko Island, South- 

 eastern Alaska, a small species of Flarpidknn is found in fairly large 

 numbers. 



This species, here named Harpidium latus, differs widely from the 

 younger stages of hoth H. insignis and H. rotundus. On the other 

 hand, being fairly conunon in a zone where hundreds of well pre- 

 served brachiopods were collected, it seems highly improbable that 

 the specimens represent immature stages of still another species of 

 large size. Measurements of a series of specimens are here given : 



Length 2. 7 cm. 



Maximum breadth 3. 1 cm. 



Maximum depth 2. 1 cm. 



The largest specimen seen, which has been badly weathered, has an 

 approximate length of 3. cm., maximum breadth of more than 3. cm., 

 and a maximum depth of about 2.5 cm. 



