ECHINODERM LARViE. 3 



canal, and can be traced from its opening into the latter to its junction with the inner 

 perihsemal ring. In none of the sections, however, can one be sure of the aboral sinus 

 or of the madreporic vesicle, though this is doubtless due to the preservation. 



Several points in the structure of these young Asterids suggest a relation to an 

 embryonic starfish studied in this laboratory some time ago by Dr. E. H. Henderson (4). 

 These were large yolky eggs of an unknown species, belonging, probably, to the genus 

 Anasterias, collected off the Franklin Islands. In the remarkably close resemblance to 

 the development of Asterina gibbosa of the same age, and in the similarity in the 

 appearance and distribution of the yolk, we have indications of a near relationship 

 between this species and Asterias brandti, but the great difference in age between the 

 two lots of embryos makes it difficult to institute a closer comparison. 



2. Ophiopluteus sp.n. (?). 

 (Fig. 2.) 



Two specimens of this presumably new Ophiopluteus were taken at the Winter 

 Quarters of the Expedition ; the first on December 15th, 1903, from No. 12 hole, in 

 8 fms. of water; the other on January 4th, 1904, from No. 13 hole, in 6 fms. The 

 first is in a comparatively good state of preservation : the second is badly disintegrated, 

 and from it alone little could be made out. It is, however, of approximately the same 

 stage of development, though a little larger, than the first. The following description 

 is, therefore, based upon the better preserved specimen. 



The body, exclusive of the arms, measures 2 • 3 mm. in length, and is marked by 

 a strongly developed conical papilla at its posterior end. 



Three pairs of arms are developed ; of these the antero-laterals and post-orals 

 are only slightly developed, but the postero-lateral pair are already equal to the body 

 in length and are widely divergent. This development of the postero-lateral arms 

 reminds us of the great size of the corresponding arms in the larva of Ophiothrix 

 fragilis, which is such an early and marked characteristic of this species. In fact, the 

 whole appearance of our specimen is strongly reminiscent of the larva of Ophiothrix. 

 The ciliated band can be traced quite distinctly bordering all the arms. 



In our better specimen the coelom can just be made out. On the left side it has 

 already divided into anterior and posterior cceloms, but on the right side it is still 

 undivided. 



The gut is well developed and shows the characteristic division into oesophagus, 

 large spherical stomach, and intestine opening on the ventral surface. 



No trace of the skeleton is preserved in these specimens, and this, together with 

 their young stage, makes classification impossible. Judging from their habitat, 

 however, and from their general appearance, they are quite possibly examples of a new 

 species. 



