188 PROCHEDINGS OF THE NATIONAL MUSEUM. VOL. 37. 
ports of Guayaquil, Paita, Callao, and Valparaiso have naturally 
been much more thoroughly explored than others. The careful col- 
lecting which would obtain the smaller species is not recorded to 
have been done anywhere at all. 
Dredging also is practicable with difficulty, except in the shel- 
tered harbors, which occur so rarely on this coast, or by the aid of a 
large steamer, which could be had only under government auspices 
on account of the great expense involved. 
The small lots of material derived from the mud which came up 
on the anchor of the U. S. Bureau of Fisheries steamer Albatross at 
one or two points, show that proper exploration will certainly reveal 
the presence of many small species, new or extra limital, which are 
at present unknown. 
In the preparation of this list I have endeavored to give a refer- 
ence to the original description and to the best available figure or 
figures. In determining what species should be included I have 
depended somewhat upon the known characteristics, as regards 
distribution, of the groups to which the species belong. For instance, 
if I found a species reported from Guayaquil and belonging to a 
widely distributed group, such as the Pholadidz, though not actually 
reported from a Peruvian locality, I have not hesitated to include 
it, knowing that in all probability it will be found on more thorough 
search in Peruvian territory. There can be little doubt that a large 
number of the more mobile of ‘he Panamic species reaching the Bay 
of Guayaquil will be found to have extended their range more or 
less within the northern border of the Peruvian Province, just as a 
certain number of the characteristic Magellanic species have traveled 
beyond their strict limits and mingle with the southern members of 
the Peruvian fauna. Species properly belonging to the Panamic 
Province and not reported as far south as Guayaquil or the Gala- 
pagos Islands have been omitted from the list. 
It will be observed that the list contains only a few minute species. 
Doubtless many of these exist, and will be found when carefully 
sought for, but, as previously indicated, the majority of collectors 
seem to have confined their attention to the more conspicuous 
species. 
I have included a certain number of pelagic forms, Cephalopods, 
Pteropods, and Nudibranchs, which are not strictly littoral, but are 
found occasionally thrown on the beaches or are captured within a 
short distance of the shore. And since collectors are certain to obtain 
them in their search for mollusks, I have added at the end of the 
list of Mollusca a list of the littoral Brachiopoda, some of which are 
so common on these shores. 
In any first census of this kind some species will be included which 
later investigation will exclude. I have rejected a number of Tschudi’s 
