148 THE VOYAGE OF H.M.S. CHALLENGER. 



Two specimens of this large species were obtained off East Moncceur Island, Bass 

 Strait, at Station 162 ; April 2, 1874 ; depth, 38 to 40 fathoms ; bottom, sand. 



Sub-family Styelin.e. 



Body attached, sessile, rarely incrusted with sand. Branchial and atrial apertures 



either four-lobed or cross-slit. 

 Test usually coriaceous, rarely cartilaginous. 

 Branchial Sac with four or less than four folds upon each side. 

 Tentacles simple, unbranched. 



This section of the Cynthiidse represents the Cynthise Styelse and Cynthise Pandocias 

 of Savigny's system, and corresponds to the genus Styela alone as used by Macleay, 

 Fleming, and Traustedt, with the addition of Pelonaia, and the new Challenger genus 

 Bathyoncus. It is a very distinct sub-family, and can be clearly distinguished from both 

 the Bolteninas and the Cynthinse by two important characters : — (l), the branchial sac has 

 never more than eight longitudinal folds, four upon each side ; and (2), the tentacles are 

 always simple. 



Savigny recognised these characters in both his third and fourth tribes of Cynthise, — the 

 Styela? and Pandocise, and Macleay, who in 1823 formed Savigny's tribes into genera, 

 distinguished those with only eight folds and unbranched tentacles from Cynthia and 

 Caesira, which had a greater number of folds and possessed compound tentacles. But 

 both these writers went on to sub-divide the group further according to the condition of 

 the genital organs. Thus Savigny distinguished the Cynthise Pandocise from the Cynthise 

 Styelse on account of the presence in the former of a single ovary placed in the intestinal 

 loop. E. Hertwig 1 has, however, shown that Savigny was mistaken as to the nature of the 

 body which he called the ovary, and probably the Pandocise agree with the Styelaa in 

 having genital glands upon both sides of the body. 



Macleay formed three genera, — Styela, with at least one ovary on each side of the 

 body ; Pandocia, with a single ovary in the intestinal loop ; and Dendrodoa, with a single 

 ovary upon the opposite side of the body. Pandocia was probably founded from Savigny's 

 mistaken account of the Cynthise Pandocise, and Dendrodoa should, I consider, be merged 

 in Styela. Various modifications of the genital glands occur among the species of this 

 genus, and I think they can scarcely be relied upon as furnishing generic characters. 



The genus Pelonaia, discovered and described by Forbes and Goodsir in 1840, and 

 investigated since by M'Intosh, Kupffer and Traustedt, seems to me to fall naturally into 

 this group. I have lately had an opportunity of dissecting Pelonaia corrugata, and it 

 appears to be closely allied to Styela, and certainly does not require a distinct family or 

 sub-family for itself. 



1 JenaischeZeitsclirift, Ed. viii. p. 96. 



