SABELLARIA SPINULOSA. 21 



where the tubes as a rule formed masses. Amongst the tubes are many other forms 

 which seek shelter in their grooves or cavities, such as Syllids, Nereids, Ephesia, 

 Pholoe, etc. 



When in its tube all the branchiae are directed forward — sloping obliquely toward 

 the middle line. The triangular lateral process in front of the first or thoracic region is 

 directed forward. The dorsal bristles follow the direction of the branchiae. On the 

 other hand, the lateral lamellae for the hooks are directed backward and flattened to the 

 sides, even the cirriform terminal ones having this tendency. The crown and its paleae 

 form an effective operculum, and even in spirit the animal cannot be released by dragging 

 it from behind. 



The closure of the tube at the posterior end is an important feature in connection 

 with the circulation of the water. When the closed end is fractured the animals fail in 

 health and frequently abandon the tube (Arnold Watson). 



On the French coast the tubes of this form are sometimes accompanied by those of 

 S. alveolata, and thus De Quatrefages confused the structure of the two species. 



Varieties. — Besides normal examples preserved on oyster-shells off St. Peter Port, 

 Guernsey, two are peculiar in having irregular crowns. In one the dorsal fissure between 

 the halves is enlarged ; the pointed papillae are present on the right, but are absent on the 

 left, with the exception of a single large one, their places being taken posteriorly by an 

 imperfect outer row of small flattened paleae which cease about half way ventralward. 

 Little regularity is observable in the left half of the crown except that a curved row of 

 the second series occurs dorsally, and a fleshy bare pad occupies the position of the inner 

 series. All the rest are irregular, but the various types of the three series are present 

 amongst them. On the right the outer row is more regular, though not normal, and the 

 individual paleae show peculiarities, such as ending in a single blunt point, though a few 

 are nearly normal. In the other example the row of pointed papillae is present on the 

 right and on the posterior half of the left. The outer paleae on the right are nearly but 

 not quite normal, the left are irregular, and the second and third series are irregular on 

 both sides. In both the condition appears to be due either to injury or congenital 

 defect. 



A specimen in the British Museum is labelled Psamatotus alveolatus, Dr. Johnston. 



Dalyell 1 (1853) appears to refer to this species under the name of Sabella aheolarla, 

 and he gives an interesting account of its tube-making, reproduction, and general habits 

 in confinement. It showed a decided preference for sand rather than pounded brick or 

 glass. 



Besides this form, Dr. Johnston (1865) described Sabellaria crassissima and figured 

 one of the paleae, but so far as can be observed it is a variety of S. spinulosa, or the author 

 has confused the two British species (De St. Joseph). Dr. Johnston considered Aheo- 

 laria lumbricalis (Mus. Leach) this form. 



De Quatrefages (1865) probably included this species under 8. alveolata. The figures 

 referred to in the synonymy pertain to S. spinulosa. The occurrence of the two 

 species in company on the shores of France led the distinguished French author to 

 confuse them. 



1 f Pow» Great./ vol. ii ; p. 176 ; pi. xxv, figs. 1 — o. 



