n 



Lytechinus pictus (Verrill). 



Oil a little (lirdging trip lo San Diego Ihe 7lh September 1915 I secured 

 a lew ri])e specinu'iis of this s])ecies; fertilization was made on board, 

 and the cnltnie carried to La .lolla. It proved lo be very good; the larva' 

 developed normally nntil the lirst stage, but then came a standstill in 

 their development, and as I had to leave La Jolla soon after, there was 

 no possibility of starting a new culture. — 



The larva was in all respects so closely like that of /.. (inamrsus, 

 I lull there was no reason for giving a special description or Hgures of 

 it. Leihaps the body rod is a lillle more branched and the recurrent 

 lod slightly smaller than in (tiuimcsiis, but the dilTerence is in any case 

 \('iy unimportant il at all constant. 



.\ls() the fully formed larva can be staled lo be closely like that of 

 (iiKduesus. On Ihe said dredging tii|) in San Diego Hay 1 found in a plankton 

 sample an Lchinoid-larva, fully developed, which had the same characters 

 in shape and skeletal slruclure as the L. (in<inu'sus-\i\r\'ii. Since at that 

 time no other ICchini than the two above named Liilcchiniis species had 

 ripe sexual j)roducts. it is beyond question that this larva also was a 

 Lytechinus larva, and the probability is. of course, that il belonged to 

 the species occurring at that place. 



Otherwise 1 wish lo express here my doubt of the distinctness of these 

 two "species". I do not see that there is any reliable dilTerence between 

 them; the typical forms. 1 agree, look very difTerent; but there are all 

 transitions between them. In my opinion L. picliis and iinamesus are 

 only the shallow water form and the deep water form or variety of one 

 and the same species. The close agreement of Iheir larvic is in conformity 

 with this view, though in itself no proof of its correctness. 



Lytechinus panamensis .Mri.sn.') 



I'l.VII Fig. 1. 



Of this, hitherto unknown, species which 1 discovered at Panama, 

 specimens conlainiiig ri|)e sexual products were found in December 191.") 

 and ferlili/alioii was made with very good result. The early developmental 

 stages, which do not |)reseiil any unusual features, pass very rapidly. 

 so that at the age of only 21 hours the embryo begins already to assume 

 the i)luleus shape. The larva in its first stage (PI. VII Fig. I) agrees very 

 closely with that of lA/lrrh. I'diicfidlus and (iimnwsus. The body is short 



') I'liis new spcck-s is distinj^uislu'd Iidiii the oilier Lytechiniis-spQcies ol the West Coast 

 of .\mc'rica in having the test uiiiforniiy reddish-lirowii coloured and tiie short spines some- 

 what handed, redhrown aii<l white. Ocular I is generally insert. It is a (|uite small form, 

 rarely exceeding 2U mm h. d.. nuist specimens being only ca. Id nun h. d. 



