246 natural history bulletin. 



Station No. 28. Sand Key light bearing N. about 6 miles; 

 116 fathoms. 



Tank 8. 



This form, which appears to be a new species, was abun- 

 dantly represented in the collection. The individuals occur 

 singly or in groups of from two to four, arising from a low 

 flat plate of coenenchyme, and are free throughout their entire 

 length (PI. in, Fig. 2). The colonies occur principally on 

 sponges, though also on tubes of Hyalincecia (?) and, in case 

 of the specimens from Station 52 on a branching, dense, cal- 

 careous substratum which seems to be a millepore, and on the 

 serpulid tubes which twined around the base of this. 



All the specimens are completely contracted, the extremity 

 of the column in the majority being flattened and marked by 

 a number of ridges radiating out from the central depression. 

 The various individuals vary somewhat in size, the largest 

 having a height of about 1.4 cm., and a diameter at the top of 

 the column of 0.5 cm., but manv individuals were only 0.2— 

 0.3 cm. in height with a diameter of about the same; grada- 

 tions between these two extremes occur in abundance. The 

 wall is firm and on a superficial view shows no trace of foreign 

 incrustation, though sections reveal foreign matter such as 

 sand and sponge spicules imbedded in the outer part of the 

 mesogloea fairly abundantly on the upper part of the column, 

 but more scantily below. The introverted portion of the 

 column has the inclusions most abundant. No trace of color 

 persists in any of the specimens. 



The tentacles are arranged in two cycles. Their muscula- 

 ture is fairly well developed, and in their mesogloea sponge 

 spicules and foraminferous shells are imbedded, especially to- 

 wards their bases, but also less abundantly throughout almost 

 their entire length. 



The mouth is large and in all the specimens examined was 

 widely open, the tips of the tentacles projecting into it (PI. in, 

 Fig. 3). The stomatodaeum is short and is furnished as usual 

 with a single siphonoglyph, moderately deep and with the 

 mesogloea of its walls considerably thickened. 



