ACADEMY OF SCIENCES. 29 



Lave reached this Academy, and the amount of zoological riches yet remain- 

 ing to be harvested in this quarter, may be guessed at from the fact that these 

 twenty species were collected incidentally, as it were, the Crustacea not being 

 the chosen field of the collector. 



It is with some diffidence that I refer some of these species to their genera, 

 simply because we have not in our collection specimens of many well known 

 genera, nor have we in our defective library any figures or description of the 

 already known species included in them. 



To make clear to others the difficulty under which I and any other person 

 who attempts to do a little original work in connection with this institution, 

 are compelled to labor, I have but to state that two of the species described 

 in this paper belong to a group of crabs, the macropodidae (distinguished by 

 the great length and thinness of their legs), no species of which has before 

 been known on this coast, but of which the typical forms are described and 

 figured in such standard works as those of Milne Edwards, and Bell's British 

 Stalk-eyed Crustacea, neither of which works are to be found in our library. 



I have, therefore, in determining the genera, been compelled to be guided 

 alone by the generic descriptions given by Dana in his Crustacea of U. S. 

 Exploring Expedition, the only comprehensive work accessible to me, and 

 that is lent to the Academy. 



Before proceeding to the technical description of the new species, I wish to 

 draw the attention of all members of the Academy at all interested in zoology, 

 to a few peculiarities in our list of native Crustacea as it stands at present. 



Two species of Macropodidae, as I have just said, are all that are yet 

 known. The crabs of this tribe are sluggish in their habits and are usually 

 found among sea weed, sponges and zoophytes, at depths below those left 

 bare at the lowest low tide, and are thus only obtained by dredging, unless 

 cast ashore in some storm along with the sea weed among which they live. 

 It is, therefore, almost a certainty that a properly organized search would 

 disclose several other species, even in this immediate neighborhood. 



Of the Xanthidae, a sub-family near the true cancer, not a single species has 

 been described by Stimpson or Dana, and it is singular that4,mong the newly 

 found San Diego species this tribe predominates. 



Only two species of the swimming crabs (Portunidae), have yet been found 

 in California, one of these (Lupa bellicosa), has been described by Stimpson, 

 and the other is new. 



The parasitic Crustacea of various orders have not yet been collected with 

 any thoroughness, but I may here mention that several, (so far as I am 

 aware) undescribed forms have recently been added to our collection, and 

 that I hope, during the course of this year, to be able to prepare another 

 paper upon them and upon other undescribed species not included in the 

 present paper. 



Neither the Entomostraca, which include the Cyclops, Cypris, Daphnis, and 

 many other tribes, nor the Barnacles or Cirripedia of this coast have yet been 

 studied, and I trust that this short enumeration of a few of the things that 

 want doing may stir up some of our members to do them. 



The collection of Crustacea in this museum now includes about 320 species, 

 almost all from this coast or from the islands of the Pacific. Scarcely any 



